Librdkafka Changelog

This page is a copy of the releases of librdkafka.

2.15.0 (2026-06-30)

KIP-932 Queues for Kafka – Now in Preview

• Added a preview implementation of the share consumer (Queues for Kafka, KIP-932). Members of a share group cooperatively consume from the same partitions with per-record acquire/acknowledge semantics and redelivery, providing queue-like consumption on top of Kafka.
• New rd_kafka_share_* public API, with a dedicated rd_kafka_share_t handle created via rd_kafka_share_consumer_new():
• Subscription: rd_kafka_share_subscribe(), rd_kafka_share_unsubscribe(), rd_kafka_share_subscription().
• Batch polling: rd_kafka_share_poll() returns an rd_kafka_messages_t batch (rd_kafka_messages_count() / rd_kafka_messages_get() / rd_kafka_messages_destroy()).
• Acknowledgement: rd_kafka_share_acknowledge(), rd_kafka_share_acknowledge_type(), rd_kafka_share_acknowledge_offset() with ACCEPT / RELEASE / REJECT types, and rd_kafka_message_delivery_count().
• Commit: rd_kafka_share_commit_sync(), rd_kafka_share_commit_async() and the acknowledgement-commit callback (rd_kafka_share_set_acknowledgement_commit_cb()).
• Lifecycle: rd_kafka_share_consumer_close(), rd_kafka_share_consumer_close_queue(), rd_kafka_share_destroy().
• Two acknowledgement modes selected by share.acknowledgement.mode (default implicit; explicit requires the application to acknowledge every record before the next poll).
• New max.poll.records property (default 500) and adjusted defaults for several network properties for share consumers (receive.message.max.bytes, connections.max.idle.ms, reconnect.backoff.ms, reconnect.backoff.max.ms).
• See the Share consumers (Queues for Kafka) section of INTRODUCTION.md, the Share consumer section in rdkafka.h, and the examples/share_consumer* programs.

[!Note] The KIP-932 share consumer is currently in Preview and should not be used in production environments. The public interfaces may change before General Availability, and known limitations apply (see INTRODUCTION.md). The share consumer is single-threaded and not thread-safe by design. It requires a broker with share groups enabled (generally available in Apache Kafka 4.2.0).

Enhancements

• Add aws_iam option to sasl.oauthbearer.metadata.authentication.type, with a defensive stub that fails when no token-refresh callback is registered.

Fixes

General fixes

• Issues: #5135. Fix compilation with CMake when CURL is disabled. The OAuthBearer OIDC code included <curl/curl.h> under #ifdef WITH_OAUTHBEARER_OIDC, but CMake always defines that macro (to 0 or 1), so CURL was required even when it was turned off. Happening since 2.11.0 (#5136).
• Issues: #5282. Fix rd_atomic32_set/rd_atomic64_set returning the new value instead of the previous one in CMake builds. CMake never defined HAVE_ATOMICS_{32,64}_ATOMIC, so the setters used a non-atomic fallback that returned the new value, which prevented the ALL_BROKERS_DOWN event from being raised under CMake. Happening since 2.11.1 (#5136).

Consumer fixes

• Issues: #5541. Improve error handling in the KIP-848 consumer group protocol:
  • Defer the leave heartbeat until the assignment is revoked, so a member that exceeds max.poll.interval.ms rejoins cleanly instead of being rejected with a fatal INVALID_REQUEST.
  • Treat GROUP_ID_NOT_FOUND in the ConsumerGroupHeartbeat response as fatal, except while the member is already leaving.
  • Surface unexpected permanent broker-level heartbeat errors instead of retrying them in a loop; internal transport/timeout codes keep their existing retry/reconnect handling. Happening since 2.12.0 (#5488)

## Checksums Release asset checksums: * v2.15.0.zip SHA256 d0655c770f7edc5699855f65b391d1e20dc24fc03ecf2dd680665934dd4d1cc1 * v2.15.0.tar.gz SHA256 259015220cdca708afe838b5aa79ebf1a5fb710fb4179cf918d390aed85d5dbc

2.14.2 (2026-06-03)

librdkafka v2.14.2 is a maintenance release:

• Fix duplicate groups in ListConsumerGroups when multiple brokers return the same group (#5417).
• Fix data race in timers (#5089).
• Update bundled OpenSSL, libcurl, zstd, zlib and cJSON dependencies (#5346).

Security considerations

Bundled dependencies were upgraded as follows (see #5346): OpenSSL 3.0.15 → 3.5.6 (LTS) for source/autoconf builds, and to 3.6.2 in vcpkg-based packages (no LTS available in vcpkg); libcurl 8.10.1 → 8.20.0 for source/autoconf builds and to 8.19.0 in vcpkg; zlib 1.3.1 → 1.3.2; zstd 1.5.6 → 1.5.7; cJSON 1.7.14 → 1.7.19.

• OpenSSL upgrade (3.0.15 → 3.5.6 LTS for source/autoconf, 3.3.2 → 3.6.2 for vcpkg) addresses:
• CVE-2025-15467 (OpenSSL): upgraded OpenSSL to 3.5.6 (LTS) or 3.6.2 with vcpkg as it usually doesn't provide LTS upgrades.
• Both branches (affect 3.0.15 and 3.3.2): CVE-2024-9143, CVE-2024-13176, CVE-2025-9230, CVE-2025-68160, CVE-2025-69418, CVE-2025-69419, CVE-2025-69420, CVE-2025-69421, CVE-2026-22795, CVE-2026-22796, CVE-2026-28387, CVE-2026-28388, CVE-2026-28389, CVE-2026-28390, CVE-2026-31789, CVE-2026-31790.

• Only the 3.3.x→3.6.2 vcpkg branch (3.0.15 was not affected): CVE-2024-12797, CVE-2025-9231, CVE-2025-15468, CVE-2025-66199.

• libcurl upgrade (8.10.1 → 8.20.0 source/autoconf, 8.10.1 → 8.19.0 vcpkg) addresses:

• CVE-2025-14017 (libcurl): solved through upgrading to CURL 8.20.0. LDAP module isn't present in pre-built binary, so this CVE doesn't affect librdkafka but can still trigger automatic scanners.
• Fixed by 8.18.0 or earlier (both autoconf and vcpkg paths): CVE-2024-9681, CVE-2024-11053, CVE-2025-0167, CVE-2025-0725, CVE-2025-4947, CVE-2025-5025, CVE-2025-10966, CVE-2025-13034, CVE-2025-14524, CVE-2025-14819, CVE-2025-15079, CVE-2025-15224, CVE-2026-1965, CVE-2026-3783, CVE-2026-3784.

• Fixed only by 8.20.0 (autoconf path); vcpkg-pinned 8.19.0 still contains these: CVE-2026-4873, CVE-2026-5545, CVE-2026-5773, CVE-2026-6253, CVE-2026-6276, CVE-2026-6429, CVE-2026-7168.

• zlib (1.3.1 → 1.3.2): CVE-2026-27171 (CPU exhaustion in crc32_combine64 and crc32_combine_gen64).

• zstd (1.5.6 → 1.5.7): no CVEs; bug-fix and performance release.

• cJSON (1.7.14 → 1.7.19): CVE-2023-50471, CVE-2023-50472, CVE-2024-31755, CVE-2025-57052.

Fixes

General fixes

• Issues: #5082. Fix data race in timers. The callback and its argument could have been modified after the lock is released. Happening since 1.x (#5089).

Consumer fixes

• Fix crash (SIGSEGV) in rd_kafka_cgrp_handle_LeaveGroup() when coordinator is unavailable during consumer close. The error logging path dereferenced a potentially NULL broker pointer. Happening since 1.x.

Admin client fixes

• Issues: #5417. Fix duplicate groups in ListConsumerGroups when multiple brokers return the same group. Happening since 1.x (#5417).

Checksums

Release asset checksums: * v2.14.2.zip SHA256 2c0a563a39d5c1bc2e7b3ae81bbad9aca23c586ddab9f659b51983d4dc67cffb * v2.14.2.tar.gz SHA256 d7eec9c31c817fa44402f679c252dfbf97e4c338a849a25c3579a31fd127beb8

2.14.1 (2026-04-15)

librdkafka v2.14.1 is a maintenance release:

• Bundle prebuilt binaries for linux-s390x (#5365).

Checksums

Release asset checksums: * v2.14.1.zip SHA256 b6f52ae7a743e504e416e620c94e1192906daf15eafe661e4e2e6a7b793efc06 * v2.14.1.tar.gz SHA256 bb246e754dee3560e9b42bf4e844dc05de4b146a3cae937e36301ffacdc456e7

2.14.0 (2026-04-01)

librdkafka v2.14.0 is a feature release:

• KIP-768 Extend SASL/OAUTHBEARER to support OIDC claim mapping beyond the default sub claim (#5336).

Checksums

Release asset checksums: * v2.14.0.zip SHA256 372589ac63b06f9cac5d9b50d4ed1998f46b1a6cca991b691527ccc62b7cb7dd * v2.14.0.tar.gz SHA256 c05c03ef00a13a8463fac3e8918c04843c416f11ced58c889d806a88ca92cf99

2.13.2 (2026-03-02)

librdkafka v2.13.2 is a maintenance release:

• The librdkafka.redist NuGet package now includes binary for alpine-arm64 (https://github.com/confluentinc/librdkafka/pull/5237, @mclayton7)
• Remove CPU usage regression when a subscription matches no topics (#5324).
• Fix rd_kafka_consume_batch_queue incorrectly updating the application position on EOF or error messages (#5213).
• Fix compilation without getentropy (@olegrok, @lpsinger, #5288).
• Use a truly random seed for pseudo-random number generation whenever available (#5288).
• Fix rd_list destroy callback type mismatch by changing rd_kafka_assignor_destroy to take a void * argument, as expected by rd_list_init() destroy callbacks, and casting internally to rd_kafka_assignor_t * (#5195) (#5278).

Fixes

General fixes

• Issues: #5283. Fix compilation without getentropy. glibc versions lacking support are those less than 2.25 (2017). Happening since 2.13.0 (@olegrok, @lpsinger, #5288).

Consumer fixes

• Issues: #5324. Remove CPU usage regression when a subscription matches no topics. The increased CPU usage (~30%) was seen in particular when there are many topics in the clusters and the given subscription regex doesn't match any. Happening since 2.10.0 (#5324).
• Issues: #4844. Fix rd_kafka_consume_batch_queue incorrectly updating the application position when receiving EOF or error messages, causing the position to move forward and likely be stored and committed. When storing the application offset the leader epoch is also considered for correct offset ordering in case of log truncation. Happening since 2.2.0 (#5213).

Checksums

Release asset checksums: * v2.13.2.zip SHA256 1b71b01a33f54c5d3e359935f73445fde4010215efdb899e3a746475d6aa178a * v2.13.2.tar.gz SHA256 14972092e4115f6e99f798a7cb420cbf6daa0c73502b3c52ae42fb5b418eea8f

2.13.0 (2026-01-05)

librdkafka v2.13.0 is a feature release:

• KIP-482 Upgrade CreateAcls, DescribeAcls, DeleteAcls to the first version supporting this KIP (#5081).
• KIP-482 Upgrade DescribeGroups, DeleteTopics, DeleteRecords, CreatePartitions, DeleteGroups to the first version supporting this KIP (#5083).
• Strip trailing dot of hostname to fix SSL certificate verification issue (#5253).
• Fix memory management for interceptors in rd_kafka_conf to prevent double-free errors (#5240).
• Fix for the pseudo-random generator seed on Windows involving as well the uniqueness of the new consumer group protocol member id (#5265).
• Add secure random generation functionality used for UUID uniqueness and secure salt generation in rd_kafka_UserScramCredentialUpsertion using OpenSSL or the POSIX or WIN32 equivalent calls when it isn't available (#5265).

Fixes

General fixes

• Issues: #4348. Strip trailing dot of hostname to fix SSL certificate verification issue. Happening since 1.x (#5253).
• Issues: #4142. Fix memory management for interceptors in rd_kafka_conf to prevent double-free errors. In case the client instance fails the users needs to destroy the configuration data structure, it was causing a double-free because the interceptors were already freed in the constructor. Happening since 1.x (#5240).
• Issues: #5263, #3929. Fix for the pseudo-random seed on Windows. The function rand_r isn't present on Windows and the global seed wasn't based on the current microseconds and thread id. Also it wasn't called on every thread as required on this platform but only once per process. The fix allows on this platform the uniqueness of client side member id generation in next-generation consumer group protocol. Happening since 1.x (#5265).

Checksums

Release asset checksums: * v2.13.0.zip SHA256 73d731322b34c59fb5245d27172c71824e9323acd934e214d70a77954749e79d * v2.13.0.tar.gz SHA256 3bd351601d8ebcbc99b9a1316cae1b83b00edbcf9411c34287edf1791c507600

New Contributors

• @fangnx made their first contribution in https://github.com/confluentinc/librdkafka/pull/5231
• @Ankith-Confluent made their first contribution in https://github.com/confluentinc/librdkafka/pull/5240

Full Changelog: https://github.com/confluentinc/librdkafka/compare/v2.12.1...v2.13.0

2.12.1 (2025-10-21)

librdkafka v2.12.1 is a maintenance release:

• Restored macOS binaries compatibility with macOS 13 and 14 (#5219).

Fixes

General fixes

• Fix to restore macOS 13 and 14 compatibility in prebuilt binaries present in librdkafka.redist. Happening since 2.12.0 (#5219).

Checksums

Release asset checksums: * v2.12.1.zip SHA256 da7571a0c1dc374aabb18af6ca01411d4bc597d321977980c8d3211ec5adf696 * v2.12.1.tar.gz SHA256 ec103fa05cb0f251e375f6ea0b6112cfc9d0acd977dc5b69fdc54242ba38a16f

2.12.0 (2025-10-08)

librdkafka v2.12.0 is a feature release:

KIP-848 – General Availability

Starting with librdkafka 2.12.0, the next generation consumer group rebalance protocol defined in KIP-848 is production-ready. Please refer the following migration guide for moving from classic to consumer protocol.

Note: The new consumer group protocol defined in KIP-848 is not enabled by default. There are few contract change associated with the new protocol and might cause breaking changes. group.protocol configuration property dictates whether to use the new consumer protocol or older classic protocol. It defaults to classic if not provided.

Enhancements and Fixes

• Support for OAUTHBEARER metadata based authentication types, starting with Azure IMDS. Introduction available (#5155).
• Fix compression types read issue in GetTelemetrySubscriptions response for big-endian architectures (#5183, @paravoid).
• Fix for KIP-1102 time based re-bootstrap condition (#5177).
• Fix for discarding the member epoch in a consumer group heartbeat response when leaving with an inflight HB (#4672).
• Fix for an error being raised after a commit due to an existing error in the topic partition (#4672).
• Fix double free of headers in rd_kafka_produceva method (@blindspotbounty, #4628).
• Fix to ensure rd_kafka_query_watermark_offsets enforces the specified timeout and does not continue beyond timeout expiry (#5201).
• New walkthrough in the Wiki about configuring Kafka cross-realm authentication between Windows SSPI and MIT Kerberos.

Fixes

General fixes

• Issues: #5178. Fix for KIP-1102 time based re-bootstrap condition. Re-bootstrap is now triggered only after metadata.recovery.rebootstrap.trigger.ms have passed since first metadata refresh request after last successful metadata response. The calculation was since last successful metadata response so it's possible it did overlap with the periodic topic.metadata.refresh.interval.ms and cause a re-bootstrap even if not needed. Happening since 2.11.0 (#5177).
• Issues: #4878. Fix to ensure rd_kafka_query_watermark_offsets enforces the specified timeout and does not continue beyond timeout expiry. Happening since 2.3.0 (#5201).

Telemetry fixes

• Issues: #5179 . Fix issue in GetTelemetrySubscriptions with big-endian architectures where wrong values are read as accepted compression types causing the metrics to be sent uncompressed. Happening since 2.5.0. Since 2.10.1 unit tests are failing when run on big-endian architectures (#5183, @paravoid).

Consumer fixes

• Issues: #5199 Fixed an issue where topic partition errors were not cleared after a successful commit. Previously, a partition could retain a stale error state even though the most recent commit succeeded, causing misleading error reporting. Now, successful commits correctly clear the error state for the affected partitions Happening since 2.4.0 (#4672).

Producer fixes

• Issues: #4627. Fix double free of headers in rd_kafka_produceva method in cases where the partition doesn't exist. Happening since 1.x (@blindspotbounty, #4628).

## Checksums Release asset checksums: * v2.12.0.zip SHA256 9b2f373e03f3d5d87c2075b3ce07ee9ea3802eea00cea41b99d8351a68d8a062 * v2.12.0.tar.gz SHA256 1355d81091d13643aed140ba0fe62437c02d9434b44e90975aaefab84c2bf237

2.11.1 (2025-08-18)

librdkafka v2.11.1 is a maintenance release:

• Made the conditions for enabling the features future proof (#5130).
• Avoid returning an all brokers down error on planned disconnections (#5126).
• An "all brokers down" error isn't returned when we haven't tried to connect to all brokers since last successful connection (#5126).

Fixes

General fixes

• Issues: #4948, #4956. Made the conditions for enabling the features future proof, allowing to remove RPC versions in a subsequent Apache Kafka version without disabling features. The existing checks were matching a single version instead of a range and were failing if the older version was removed. Happening since 1.x (#5130).

• Issues: #5142. Avoid returning an all brokers down error on planned disconnections. This is done by avoiding to count planned disconnections, such as idle disconnections, broker host change and similar as events that can cause the client to reach the "all brokers down" state, returning an error and since 2.10.0 possibly starting a re-bootstrap sequence. Happening since 1.x (#5126).

• Issues: #5142. An "all brokers down" error isn't returned when we haven't tried to connect to all brokers since last successful connection. It happened because the down state is cached and can be stale when a connection isn't needed to that particular broker. Solved by resetting the cached broker down state when any broker successfully connects, so that broker needs to be tried again. Happening since 1.x (#5126).

Checksums

Release asset checksums: * v2.11.1.zip SHA256 4a63e4422e5f5bbbb47f0ac1200e2ebd1f91b7b23f0de1bc625810c943fb870e * v2.11.1.tar.gz SHA256 a2c87186b081e2705bb7d5338d5a01bc88d43273619b372ccb7bb0d264d0ca9f

2.11.0 (2025-07-03)

librdkafka v2.11.0 is a feature release:

• KIP-1102 Enable clients to rebootstrap based on timeout or error code (#4981).
• KIP-1139 Add support for OAuth jwt-bearer grant type (#4978).
• Fix for poll ratio calculation in case the queues are forwarded (#5017).
• Fix data race when buffer queues are being reset instead of being initialized (#4718).
• Features BROKER_BALANCED_CONSUMER and SASL_GSSAPI don't depend on JoinGroup v0 anymore, missing in AK 4.0 and CP 8.0 (#5131).
• Improve HTTPS CA certificates configuration by probing several paths when OpenSSL is statically linked and providing a way to customize their location or value (#5133).

Fixes

General fixes

• Issues: #4522. A data race happened when emptying buffers of a failing broker, in its thread, with the statistics callback in main thread gathering the buffer counts. Solved by resetting the atomic counters instead of initializing them. Happening since 1.x (#4718).
• Issues: #4948 Features BROKER_BALANCED_CONSUMER and SASL_GSSAPI don't depend on JoinGroup v0 anymore, missing in AK 4.0 and CP 8.0. This PR partially fixes the linked issue, a complete fix for all features will follow. Rest of fixes are necessary only for a subsequent Apache Kafka major version (e.g. AK 5.x). Happening since 1.x (#5131).

Telemetry fixes

• Issues: #5109 Fix for poll ratio calculation in case the queues are forwarded. Poll ratio is now calculated per-queue instead of per-instance and it allows to avoid calculation problems linked to using the same field. Happens since 2.6.0 (#5017).

Checksums

Release asset checksums: * v2.11.0.zip SHA256 9e76a408f0ed346f21be5e2df58b672d07ff9c561a5027f16780d1b26ef24683 * v2.11.0.tar.gz SHA256 592a823dc7c09ad4ded1bc8f700da6d4e0c88ffaf267815c6f25e7450b9395ca

2.10.1 (2025-06-11)

librdkafka v2.10.1 is a maintenance release:

• Fix to add locks when updating the metadata cache for the consumer after no broker connection is available (@marcin-krystianc, #5066).
• Fix to the re-bootstrap case when bootstrap.servers is NULL and brokers were added manually through rd_kafka_brokers_add (#5067).
• Fix an issue where the first message to any topic produced via producev or produceva was delivered late (by up to 1 second) (#5032).
• Fix for a loop of re-bootstrap sequences in case the client reaches the all brokers down state (#5086).
• Fix for frequent disconnections on push telemetry requests with particular metric configurations (#4912).
• Avoid copy outside boundaries when reading metric names in telemetry subscription (#5105)
• Metrics aren't duplicated when multiple prefixes match them (#5104)

Fixes

General fixes

• Issues: #5088. Fix for a loop of re-bootstrap sequences in case the client reaches the all brokers down state. The client continues to select the bootstrap brokers given they have no connection attempt and doesn't re-connect to the learned ones. In case it happens a broker restart can break the loop for the clients using the affected version. Fixed by giving a higher chance to connect to the learned brokers even if there are new ones that never tried to connect. Happens since 2.10.0 (#5086).
• Issues: #5057. Fix to the re-bootstrap case when bootstrap.servers is NULL and brokers were added manually through rd_kafka_brokers_add. Avoids a segmentation fault in this case. Happens since 2.10.0 (#5067).

Producer fixes

• In case of producev or produceva, the producer did not enqueue a leader query metadata request immediately, and rather, waited for the 1 second timer to kick in. This could cause delays in the sending of the first message by up to 1 second. Happens since 1.x (#5032).

Consumer fixes

• Issues: #5051. Fix to add locks when updating the metadata cache for the consumer. It can cause memory corruption or use-after-free in case there's no broker connection and the consumer group metadata needs to be updated. Happens since 2.10.0 (#5066).

Telemetry fixes

• Issues: #5106. Fix for frequent disconnections on push telemetry requests with particular metric configurations. A NULL payload is sent in a push telemetry request when an empty one is needed. This causes disconnections every time the push is sent, only when metrics are requested and some metrics are matching the producer but none the consumer or the other way around. Happens since 2.5.0 (#4912).
• Issues: #5102. Avoid copy outside boundaries when reading metric names in telemetry subscription. It can cause that some metrics aren't matched. Happens since 2.5.0 (#5105).
• Issues: #5103. Telemetry metrics aren't duplicated when multiple prefixes match them. Fixed by keeping track of the metrics that already matched. Happens since 2.5.0 (#5104).

Checksums

Release asset checksums: * v2.10.1.zip SHA256 7cb72c4f3d162f50d30d81fd7f7ba0f3d9e8ecd09d9b4c5af7933314e24dd0ba * v2.10.1.tar.gz SHA256 75f59a2d948276504afb25bcb5713a943785a413b84f9099d324d26b2021f758

2.10.0 (2025-04-17)

librdkafka v2.10.0 is a feature release:

KIP-848 – Now in Preview

• KIP-848 has transitioned from Early Access to Preview.
• Added support for regex-based subscriptions.
• Implemented client-side member ID generation as per KIP-1082.
• rd_kafka_DescribeConsumerGroups() now supports KIP-848-style consumer groups. Two new fields have been added:
• Group type – Indicates whether the group is classic or consumer.
• Target assignment – Applicable only to consumer protocol groups (defaults to NULL).
• Group configuration is now supported in AlterConfigs, IncrementalAlterConfigs, and DescribeConfigs. (#4939)
• Added Topic Authorization Error support in the ConsumerGroupHeartbeat response.
• Removed usage of the partition.assignment.strategy property for the consumer group protocol. An error will be raised if this is set with group.protocol=consumer.
• Deprecated and disallowed the following properties for the consumer group protocol:
• session.timeout.ms
• heartbeat.interval.ms
• group.protocol.type
  Attempting to set any of these will result in an error.
• Enhanced handling for subscribe() and unsubscribe() edge cases.

[!Note] The KIP-848 consumer is currently in Preview and should not be used in production environments. Implementation is feature complete but contract could have minor changes before General Availability.

## Enhancements and Fixes

• Identify brokers only by broker id (#4557, @mfleming)
• Remove unavailable brokers and their thread (#4557, @mfleming)
• Commits during a cooperative incremental rebalance aren't causing an assignment lost if the generation id was bumped in between (#4908).
• Fix for librdkafka yielding before timeouts had been reached (#4970)
• Removed a 500ms latency when a consumer partition switches to a different leader (#4970)
• The mock cluster implementation removes brokers from Metadata response when they're not available, this simulates better the actual behavior of a cluster that is using KRaft (#4970).
• Doesn't remove topics from cache on temporary Metadata errors but only on metadata cache expiry (#4970).
• Doesn't mark the topic as unknown if it had been marked as existent earlier and topic.metadata.propagation.max.ms hasn't passed still (@marcin-krystianc, #4970).
• Doesn't update partition leaders if the topic in metadata response has errors (#4970).
• Only topic authorization errors in a metadata response are considered permanent and are returned to the user (#4970).
• The function rd_kafka_offsets_for_times refreshes leader information if the error requires it, allowing it to succeed on subsequent manual retries (#4970).
• Deprecated api.version.request, api.version.fallback.ms and broker.version.fallback configuration properties (#4970).
• When consumer is closed before destroying the client, the operations queue isn't purged anymore as it contains operations unrelated to the consumer group (#4970).
• When making multiple changes to the consumer subscription in a short time, no unknown topic error is returned for topics that are in the new subscription but weren't in previous one (#4970).
• Prevent metadata cache corruption when topic id changes (@kwdubuc, @marcin-krystianc, @GerKr, #4970).
• Fix for the case where a metadata refresh enqueued on an unreachable broker prevents refreshing the controller or the coordinator until that broker becomes reachable again (#4970).
• Remove a one second wait after a partition fetch is restarted following a leader change and offset validation (#4970).
• Fix the Nagle algorithm (TCP_NODELAY) on broker sockets to not be enabled by default (#4986).

Fixes

General fixes

• Issues: #4212 Identify brokers only by broker id, as happens in Java, avoid to find the broker with same hostname and use the same thread and connection. Happens since 1.x (#4557, @mfleming).
• Issues: #4557 Remove brokers not reported in a metadata call, along with their thread. Avoids that unavailable brokers are selected for a new connection when there's no one available. We cannot tell if a broker was removed temporarily or permanently so we always remove it and it'll be added back when it becomes available again. Happens since 1.x (#4557, @mfleming).
• Issues: #4970 librdkafka code using cnd_timedwait was yielding before a timeout occurred without the condition being fulfilled because of spurious wake-ups. Solved by verifying with a monotonic clock that the expected point in time was reached and calling the function again if needed. Happens since 1.x (#4970).
• Issues: #4970 Doesn't remove topics from cache on temporary Metadata errors but only on metadata cache expiry. It allows the client to continue working in case of temporary problems to the Kafka metadata plane. Happens since 1.x (#4970).
• Issues: #4970 Doesn't mark the topic as unknown if it had been marked as existent earlier and topic.metadata.propagation.max.ms hasn't passed still. It achieves this property expected effect even if a different broker had previously reported the topic as existent. Happens since 1.x (@marcin-krystianc, #4970).
• Issues: #4907 Doesn't update partition leaders if the topic in metadata response has errors. It's in line with what Java client does and allows to avoid segmentation faults for unknown partitions. Happens since 1.x (#4970).
• Issues: #4970 Only topic authorization errors in a metadata response are considered permanent and are returned to the user. It's in line with what Java client does and avoids returning to the user an error that wasn't meant to be permanent. Happens since 1.x (#4970).
• Issues: #4964, #4778 Prevent metadata cache corruption when topic id for the same topic name changes. Solved by correctly removing the entry with the old topic id from metadata cache to prevent subsequent use-after-free. Happens since 2.4.0 (@kwdubuc, @marcin-krystianc, @GerKr, #4970).
• Issues: #4970 Fix for the case where a metadata refresh enqueued on an unreachable broker prevents refreshing the controller or the coordinator until that broker becomes reachable again. Given the request continues to be retried on that broker, the counter for refreshing complete broker metadata doesn't reach zero and prevents the client from obtaining the new controller or group or transactional coordinator. It causes a series of debug messages like: "Skipping metadata request: ... full request already in-transit", until the broker the request is enqueued on is up again. Solved by not retrying these kinds of metadata requests. Happens since 1.x (#4970).
• The Nagle algorithm (TCP_NODELAY) is now disabled by default. It caused a large increase in latency for some use cases, for example, when using an SSL connection. For efficient batching, the application should use linger.ms, batch.size etc. Happens since: 0.x (#4986).

Consumer fixes

• Issues: #4059 Commits during a cooperative incremental rebalance could cause an assignment lost if the generation id was bumped by a second join group request. Solved by not rejoining the group in case an illegal generation error happens during a rebalance. Happening since v1.6.0 (#4908)
• Issues: #4970 When switching to a different leader a consumer could wait 500ms (fetch.error.backoff.ms) before starting to fetch again. The fetch backoff wasn't reset when joining the new broker. Solved by resetting it, given it's not needed to backoff the first fetch on a different node. This way faster leader switches are possible. Happens since 1.x (#4970).
• Issues: #4970 The function rd_kafka_offsets_for_times refreshes leader information if the error requires it, allowing it to succeed on subsequent manual retries. Similar to the fix done in 2.3.0 in rd_kafka_query_watermark_offsets. Additionally, the partition current leader epoch is taken from metadata cache instead of from passed partitions. Happens since 1.x (#4970).
• Issues: #4970 When consumer is closed before destroying the client, the operations queue isn't purged anymore as it contains operations unrelated to the consumer group. Happens since 1.x (#4970).
• Issues: #4970 When making multiple changes to the consumer subscription in a short time, no unknown topic error is returned for topics that are in the new subscription but weren't in previous one. This was due to the metadata request relative to previous subscription. Happens since 1.x (#4970).
• Issues: #4970 Remove a one second wait after a partition fetch is restarted following a leader change and offset validation. This is done by resetting the fetch error backoff and waking up the delegated broker if present. Happens since 2.1.0 (#4970).

Note: there was no v2.9.0 librdkafka release, it was a dependent clients release only

Checksums

Release asset checksums: * v2.10.0.zip SHA256 e30944f39b353ee06e70861348011abfc32d9ab6ac850225b0666e9d97b9090d * v2.10.0.tar.gz SHA256 004b1cc2685d1d6d416b90b426a0a9d27327a214c6b807df6f9ea5887346ba3a

2.8.0 (2025-01-07)

librdkafka v2.8.0 is a maintenance release:

• Socket options are now all set before connection (#4893).
• Client certificate chain is now sent when using ssl.certificate.pem or ssl_certificate or ssl.keystore.location (#4894).
• Avoid sending client certificates whose chain doesn't match with broker trusted root certificates (#4900).
• Fixes to allow to migrate partitions to leaders with same leader epoch, or NULL leader epoch (#4901).
• Support versions of OpenSSL without the ENGINE component (Chris Novakovic, #3535 and @remicollet, #4911).

Fixes

General fixes

• Socket options are now all set before connection, as documentation says it's needed for socket buffers to take effect, even if in some cases they could have effect even after connection. Happening since v0.9.0 (#4893).
• Issues: #3225. Client certificate chain is now sent when using ssl.certificate.pem or ssl_certificate or ssl.keystore.location. Without that, broker must explicitly add any intermediate certification authority certificate to its truststore to be able to accept client certificate. Happens since: 1.x (#4894).

Consumer fixes

• Issues: #4796. Fix to allow to migrate partitions to leaders with NULL leader epoch. NULL leader epoch can happen during a cluster roll with an upgrade to a version supporting KIP-320. Happening since v2.1.0 (#4901).
• Issues: #4804. Fix to allow to migrate partitions to leaders with same leader epoch. Same leader epoch can happen when partition is temporarily migrated to the internal broker (#4804), or if broker implementation never bumps it, as it's not needed to validate the offsets. Happening since v2.4.0 (#4901).

Note: there was no v2.7.0 librdkafka release

Checksums

Release asset checksums: * v2.8.0.zip SHA256 5525efaad154e277e6ce30ab78bb00dbd882b5eeda6c69c9eeee69b7abee11a4 * v2.8.0.tar.gz SHA256 5bd1c46f63265f31c6bfcedcde78703f77d28238eadf23821c2b43fc30be3e25

2.2.1 (2025-01-13)

Note: given this patch version contains only a single fix, it's suggested to upgrade to latest backward compatible release instead, as it contains all the issued fixes. Following semver 2.0, all our patch and minor releases are backward compatible and our minor releases may also contain fixes. Please note that 2.x versions of librdkafka are also backward compatible with 1.x as the major version release was only for the upgrade to OpenSSL 3.x.

librdkafka v2.2.1 is a maintenance release backporting:

• Fix for idempotent producer fatal errors, triggered after a possibly persisted message state (#4438).
• Update bundled lz4 (used when ./configure --disable-lz4-ext) to v1.9.4, which contains bugfixes and performance improvements (#4726).
• Upgrade OpenSSL to v3.0.13 (while building from source) with various security fixes, check the release notes (@janjwerner-confluent, #4690).
• Upgrade zstd to v1.5.6, zlib to v1.3.1, and curl to v8.8.0 (@janjwerner-confluent, #4690).
• Upgrade Linux dependencies: OpenSSL 3.0.15, CURL 8.10.1 (#4875).

Checksums

Release asset checksums: * v2.2.1.zip SHA256 2d7fdb54b17be8442b61649916b94eda1744c21d2325795d92f9ad6dec4e5621 * v2.2.1.tar.gz SHA256 c6f0ccea730ce8f67333e75cc785cce28a8941d5abf041d7a9b8fef91d4778e8

2.6.1 (2024-11-18)

librdkafka v2.6.1 is a maintenance release:

• Fix for a Fetch regression when connecting to Apache Kafka < 2.7 (#4871).
• Fix for an infinite loop happening with cooperative-sticky assignor under some particular conditions (#4800).
• Fix for retrieving offset commit metadata when it contains zeros and configured with strndup (#4876)
• Fix for a loop of ListOffset requests, happening in a Fetch From Follower scenario, if such request is made to the follower (#4616, #4754, @kphelps).
• Fix to remove fetch queue messages that blocked the destroy of rdkafka instances (#4724)
• Upgrade Linux dependencies: OpenSSL 3.0.15, CURL 8.10.1 (#4875).
• Upgrade Windows dependencies: MSVC runtime to 14.40.338160.0, zstd 1.5.6, zlib 1.3.1, OpenSSL 3.3.2, CURL 8.10.1 (#4872).
• SASL/SCRAM authentication fix: avoid concatenating client side nonce once more, as it's already prepended in server sent nonce (#4895).
• Allow retrying for status code 429 ('Too Many Requests') in HTTP requests for OAUTHBEARER OIDC (#4902).

Fixes

General fixes

• SASL/SCRAM authentication fix: avoid concatenating client side nonce once more, as it's already prepended in server sent nonce. librdkafka was incorrectly concatenating the client side nonce again, leading to this fix being made on AK side, released with 3.8.1, with endsWith instead of equals. Happening since v0.0.99 (#4895).

Consumer fixes

• Issues: #4870 Fix for a Fetch regression when connecting to Apache Kafka < 2.7, causing fetches to fail. Happening since v2.6.0 (#4871)
• Issues: #4783. A consumer configured with the cooperative-sticky partition assignment strategy could get stuck in an infinite loop, with corresponding spike of main thread CPU usage. That happened with some particular orders of members and potential assignable partitions. Solved by removing the infinite loop cause. Happening since: 1.6.0 (#4800).
• Issues: #4649. When retrieving offset metadata, if the binary value contained zeros and librdkafka was configured with strndup, part of the buffer after first zero contained uninitialized data instead of rest of metadata. Solved by avoiding to use strndup for copying metadata. Happening since: 0.9.0 (#4876).
• Issues: #4616 When an out of range on a follower caused an offset reset, the corresponding ListOffsets request is made to the follower, causing a repeated "Not leader for partition" error. Fixed by sending the request always to the leader. Happening since 1.5.0 (tested version) or previous ones (#4616, #4754, @kphelps).
• Issues: Fix to remove fetch queue messages that blocked the destroy of rdkafka instances. Circular dependencies from a partition fetch queue message to the same partition blocked the destroy of an instance, that happened in case the partition was removed from the cluster while it was being consumed. Solved by purging internal partition queue, after being stopped and removed, to allow reference count to reach zero and trigger a destroy. Happening since 2.0.2 (#4724).

Checksums

Release asset checksums: * v2.6.1.zip SHA256 b575811865d9c0439040ccb2972ae6af963bc58ca39d433243900dddfdda79cf * v2.6.1.tar.gz SHA256 0ddf205ad8d36af0bc72a2fec20639ea02e1d583e353163bf7f4683d949e901b

2.6.0 (2024-10-10)

librdkafka v2.6.0 is a feature release:

• KIP-460 Admin Leader Election RPC (#4845)
• [KIP-714] Complete consumer metrics support (#4808).
• [KIP-714] Produce latency average and maximum metrics support for parity with Java client (#4847).
• [KIP-848] ListConsumerGroups Admin API now has an optional filter to return only groups of given types.
• Added Transactional id resource type for ACL operations (@JohnPreston, #4856).
• Fix for permanent fetch errors when using a newer Fetch RPC version with an older inter broker protocol (#4806).

Fixes

Consumer fixes

• Issues: #4806 Fix for permanent fetch errors when brokers support a Fetch RPC version greater than 12 but cluster is configured to use an inter broker protocol that is less than 2.8. In this case returned topic ids are zero valued and Fetch has to fall back to version 12, using topic names. Happening since v2.5.0 (#4806)

Checksums

Release asset checksums: * v2.6.0.zip SHA256 e9eb7faedb24da3a19d5f056e08630fc2dae112d958f9b714ec6e35cd87c032e * v2.6.0.tar.gz SHA256 abe0212ecd3e7ed3c4818a4f2baf7bf916e845e902bb15ae48834ca2d36ac745

2.5.3 (2024-09-02)

librdkafka v2.5.3 is a maintenance release.

• Fix an assert being triggered during push telemetry call when no metrics matched on the client side. (#4826)

Fixes

Telemetry fixes

• Issue: #4833 Fix a regression introduced with KIP-714 support in which an assert is triggered during PushTelemetry call. This happens when no metric is matched on the client side among those requested by broker subscription. Happening since 2.5.0 (#4826).

Checksums

Release asset checksums: * v2.5.3.zip SHA256 5b058006fcd403bc23fc1fcc14fe985641203f342c5715794af51023bcd047f9 * v2.5.3.tar.gz SHA256 eaa1213fdddf9c43e28834d9a832d9dd732377d35121e42f875966305f52b8ff

Note: there were no v2.5.1 and v2.5.2 librdkafka releases

2.5.0 (2024-07-10)

[!WARNING] This version has introduced a regression in which an assert is triggered during PushTelemetry call. This happens when no metric is matched on the client side among those requested by broker subscription.

You won't face any problem if: * Broker doesn't support KIP-714. * KIP-714 feature is disabled on the broker side. * KIP-714 feature is disabled on the client side. This is enabled by default. Set configuration enable.metrics.push to false. * If KIP-714 is enabled on the broker side and there is no subscription configured there. * If KIP-714 is enabled on the broker side with subscriptions that match the KIP-714 metrics defined on the client.

Having said this, we strongly recommend using v2.5.3 and above to not face this regression at all.

librdkafka v2.5.0 is a feature release.

• KIP-951 Leader discovery optimisations for the client (#4756, #4767).
• Fix segfault when using long client id because of erased segment when using flexver. (#4689)
• Fix for an idempotent producer error, with a message batch not reconstructed identically when retried (#4750)
• Removed support for CentOS 6 and CentOS 7 (#4775).
• KIP-714 Client metrics and observability (#4721).

Upgrade considerations

• CentOS 6 and CentOS 7 support was removed as they reached EOL and security patches aren't publicly available anymore. ABI compatibility from CentOS 8 on is maintained through pypa/manylinux, AlmaLinux based. See also Confluent supported OSs page (#4775).

Enhancements

• Update bundled lz4 (used when ./configure --disable-lz4-ext) to v1.9.4, which contains bugfixes and performance improvements (#4726).
• KIP-951 With this KIP leader updates are received through Produce and Fetch responses in case of errors corresponding to leader changes and a partition migration happens before refreshing the metadata cache (#4756, #4767).

Fixes

General fixes

• Issues: confluentinc/confluent-kafka-dotnet#2084 Fix segfault when a segment is erased and more data is written to the buffer. Happens since 1.x when a portion of the buffer (segment) is erased for flexver or compression. More likely to happen since 2.1.0, because of the upgrades to flexver, with certain string sizes like a long client id (#4689).

Idempotent producer fixes

• Issues: #4736 Fix for an idempotent producer error, with a message batch not reconstructed identically when retried. Caused the error message "Local: Inconsistent state: Unable to reconstruct MessageSet". Happening on large batches. Solved by using the same backoff baseline for all messages in the batch. Happens since 2.2.0 (#4750).

Checksums

Release asset checksums: * v2.5.0.zip SHA256 644c1b7425e2241ee056cf8a469c84d69c7f6a88559491c0813a6cdeb5563206 * v2.5.0.tar.gz SHA256 3dc62de731fd516dfb1032861d9a580d4d0b5b0856beb0f185d06df8e6c26259

2.4.0 (2024-05-07)

librdkafka v2.4.0 is a feature release:

• KIP-848: The Next Generation of the Consumer Rebalance Protocol. Early Access: This should be used only for evaluation and must not be used in production. Features and contract of this KIP might change in future (#4610).
• KIP-467: Augment ProduceResponse error messaging for specific culprit records (#4583).
• KIP-516 Continue partial implementation by adding a metadata cache by topic id and updating the topic id corresponding to the partition name (#4676)
• Upgrade OpenSSL to v3.0.12 (while building from source) with various security fixes, check the release notes.
• Integration tests can be started in KRaft mode and run against any GitHub Kafka branch other than the released versions.
• Fix pipeline inclusion of static binaries (#4666)
• Fix to main loop timeout calculation leading to a tight loop for a max period of 1 ms (#4671).
• Fixed a bug causing duplicate message consumption from a stale fetch start offset in some particular cases (#4636)
• Fix to metadata cache expiration on full metadata refresh (#4677).
• Fix for a wrong error returned on full metadata refresh before joining a consumer group (#4678).
• Fix to metadata refresh interruption (#4679).
• Fix for an undesired partition migration with stale leader epoch (#4680).
• Fix hang in cooperative consumer mode if an assignment is processed while closing the consumer (#4528).

Upgrade considerations

• With KIP 467, INVALID_MSG (Java: CorruptRecordExpection) will be retried automatically. INVALID_RECORD (Java: InvalidRecordException) instead is not retriable and will be set only to the records that caused the error. Rest of records in the batch will fail with the new error code _INVALID_DIFFERENT_RECORD (Java: KafkaException) and can be retried manually, depending on the application logic (#4583).

Early Access

KIP-848: The Next Generation of the Consumer Rebalance Protocol

• With this new protocol the role of the Group Leader (a member) is removed and the assignment is calculated by the Group Coordinator (a broker) and sent to each member through heartbeats.

The feature is still not production-ready. It's possible to try it in a non-production enviroment.

A guide is available with considerations and steps to follow to test it (#4610).

Fixes

General fixes

• Issues: confluentinc/confluent-kafka-go#981. In librdkafka release pipeline a static build containing libsasl2 could be chosen instead of the alternative one without it. That caused the libsasl2 dependency to be required in confluent-kafka-go v2.1.0-linux-musl-arm64 and v2.3.0-linux-musl-arm64. Solved by correctly excluding the binary configured with that library, when targeting a static build. Happening since v2.0.2, with specified platforms, when using static binaries (#4666).
• Issues: #4684. When the main thread loop was awakened less than 1 ms before the expiration of a timeout, it was serving with a zero timeout, leading to increased CPU usage until the timeout was reached. Happening since 1.x.
• Issues: #4685. Metadata cache was cleared on full metadata refresh, leading to unnecessary refreshes and occasional UNKNOWN_TOPIC_OR_PART errors. Solved by updating cache for existing or hinted entries instead of clearing them. Happening since 2.1.0 (#4677).
• Issues: #4589. A metadata call before member joins consumer group, could lead to an UNKNOWN_TOPIC_OR_PART error. Solved by updating the consumer group following a metadata refresh only in safe states. Happening since 2.1.0 (#4678).
• Issues: #4577. Metadata refreshes without partition leader change could lead to a loop of metadata calls at fixed intervals. Solved by stopping metadata refresh when all existing metadata is non-stale. Happening since 2.3.0 (#4679).
• Issues: #4687. A partition migration could happen, using stale metadata, when the partition was undergoing a validation and being retried because of an error. Solved by doing a partition migration only with a non-stale leader epoch. Happening since 2.1.0 (#4680).

Consumer fixes

• Issues: #4686. In case of subscription change with a consumer using the cooperative assignor it could resume fetching from a previous position. That could also happen if resuming a partition that wasn't paused. Fixed by ensuring that a resume operation is completely a no-op when the partition isn't paused. Happening since 1.x (#4636).
• Issues: #4527. While using the cooperative assignor, given an assignment is received while closing the consumer it's possible that it gets stuck in state WAIT_ASSIGN_CALL, while the method is converted to a full unassign. Solved by changing state from WAIT_ASSIGN_CALL to WAIT_UNASSIGN_CALL while doing this conversion. Happening since 1.x (#4528).

Checksums

Release asset checksums: * v2.4.0.zip SHA256 24b30d394fc6ce5535eaa3c356ed9ed9ae4a6c9b4fc9159c322a776786d5dd15 * v2.4.0.tar.gz SHA256 d645e47d961db47f1ead29652606a502bdd2a880c85c1e060e94eea040f1a19a

2.3.0 (2023-10-25)

librdkafka v2.3.0 is a feature release:

• KIP-516 Partial support of topic identifiers. Topic identifiers in metadata response available through the new rd_kafka_DescribeTopics function (#4300, #4451).
• KIP-117 Add support for AdminAPI DescribeCluster() and DescribeTopics() (#4240, @jainruchir).
• KIP-430: Return authorized operations in Describe Responses. (#4240, @jainruchir).
• KIP-580: Added Exponential Backoff mechanism for retriable requests with retry.backoff.ms as minimum backoff and retry.backoff.max.ms as the maximum backoff, with 20% jitter (#4422).
• KIP-396: completed the implementation with the addition of ListOffsets (#4225).
• Fixed ListConsumerGroupOffsets not fetching offsets for all the topics in a group with Apache Kafka version below 2.4.0.
• Add missing destroy that leads to leaking partition structure memory when there are partition leader changes and a stale leader epoch is received (#4429).
• Fix a segmentation fault when closing a consumer using the cooperative-sticky assignor before the first assignment (#4381).
• Fix for insufficient buffer allocation when allocating rack information (@wolfchimneyrock, #4449).
• Fix for infinite loop of OffsetForLeaderEpoch requests on quick leader changes. (#4433).
• Fix to add leader epoch to control messages, to make sure they're stored for committing even without a subsequent fetch message (#4434).
• Fix for stored offsets not being committed if they lacked the leader epoch (#4442).
• Upgrade OpenSSL to v3.0.11 (while building from source) with various security fixes, check the release notes (#4454, started by @migarc1).
• Fix to ensure permanent errors during offset validation continue being retried and don't cause an offset reset (#4447).
• Fix to ensure max.poll.interval.ms is reset when rd_kafka_poll is called with consume_cb (#4431).
• Fix for idempotent producer fatal errors, triggered after a possibly persisted message state (#4438).
• Fix rd_kafka_query_watermark_offsets continuing beyond timeout expiry (#4460).
• Fix rd_kafka_query_watermark_offsets not refreshing the partition leader after a leader change and subsequent NOT_LEADER_OR_FOLLOWER error (#4225).

Upgrade considerations

• retry.backoff.ms: If it is set greater than retry.backoff.max.ms which has the default value of 1000 ms then it is assumes the value of retry.backoff.max.ms. To change this behaviour make sure that retry.backoff.ms is always less than retry.backoff.max.ms. If equal then the backoff will be linear instead of exponential.

• topic.metadata.refresh.fast.interval.ms: If it is set greater than retry.backoff.max.ms which has the default value of 1000 ms then it is assumes the value of retry.backoff.max.ms. To change this behaviour make sure that topic.metadata.refresh.fast.interval.ms is always less than retry.backoff.max.ms. If equal then the backoff will be linear instead of exponential.

Fixes

General fixes

• An assertion failed with insufficient buffer size when allocating rack information on 32bit architectures. Solved by aligning all allocations to the maximum allowed word size (#4449).
• The timeout for rd_kafka_query_watermark_offsets was not enforced after making the necessary ListOffsets requests, and thus, it never timed out in case of broker/network issues. Fixed by setting an absolute timeout (#4460).

Idempotent producer fixes

• After a possibly persisted error, such as a disconnection or a timeout, next expected sequence used to increase, leading to a fatal error if the message wasn't persisted and the second one in queue failed with an OUT_OF_ORDER_SEQUENCE_NUMBER. The error could contain the message "sequence desynchronization" with just one possibly persisted error or "rewound sequence number" in case of multiple errored messages. Solved by treating the possible persisted message as not persisted, and expecting a DUPLICATE_SEQUENCE_NUMBER error in case it was or NO_ERROR in case it wasn't, in both cases the message will be considered delivered (#4438).

Consumer fixes

• Stored offsets were excluded from the commit if the leader epoch was less than committed epoch, as it's possible if leader epoch is the default -1. This didn't happen in Python, Go and .NET bindings when stored position was taken from the message. Solved by checking only that the stored offset is greater than committed one, if either stored or committed leader epoch is -1 (#4442).
• If an OffsetForLeaderEpoch request was being retried, and the leader changed while the retry was in-flight, an infinite loop of requests was triggered, because we weren't updating the leader epoch correctly. Fixed by updating the leader epoch before sending the request (#4433).
• During offset validation a permanent error like host resolution failure would cause an offset reset. This isn't what's expected or what the Java implementation does. Solved by retrying even in case of permanent errors (#4447).
• If using rd_kafka_poll_set_consumer, along with a consume callback, and then calling rd_kafka_poll to service the callbacks, would not reset max.poll.interval.ms. This was because we were only checking rk_rep for consumer messages, while the method to service the queue internally also services the queue forwarded to from rk_rep, which is rkcg_q. Solved by moving the max.poll.interval.ms check into rd_kafka_q_serve (#4431).
• After a leader change a rd_kafka_query_watermark_offsets call would continue trying to call ListOffsets on the old leader, if the topic wasn't included in the subscription set, so it started querying the new leader only after topic.metadata.refresh.interval.ms (#4225).

Checksums

Release asset checksums: * v2.3.0.zip SHA256 15e77455811b3e5d869d6f97ce765b634c7583da188792e2930a2098728e932b * v2.3.0.tar.gz SHA256 2d49c35c77eeb3d42fa61c43757fcbb6a206daa560247154e60642bcdcc14d12

2.2.0 (2023-07-12)

librdkafka v2.2.0 is a feature release:

• Fix a segmentation fault when subscribing to non-existent topics and using the consume batch functions (#4273).
• Store offset commit metadata in rd_kafka_offsets_store (@mathispesch, #4084).
• Fix a bug that happens when skipping tags, causing buffer underflow in MetadataResponse (#4278).
• Fix a bug where topic leader is not refreshed in the same metadata call even if the leader is present.
• KIP-881: Add support for rack-aware partition assignment for consumers (#4184, #4291, #4252).
• Fix several bugs with sticky assignor in case of partition ownership changing between members of the consumer group (#4252).
• KIP-368: Allow SASL Connections to Periodically Re-Authenticate (#4301, started by @vctoriawu).
• Avoid treating an OpenSSL error as a permanent error and treat unclean SSL closes as normal ones (#4294).
• Added fetch.queue.backoff.ms to the consumer to control how long the consumer backs off next fetch attempt. (@bitemyapp, @edenhill, #2879)
• KIP-235: Add DNS alias support for secured connection (#4292).
• KIP-339: IncrementalAlterConfigs API (started by @PrasanthV454, #4110).
• KIP-554: Add Broker-side SCRAM Config API (#4241).

Enhancements

• Added fetch.queue.backoff.ms to the consumer to control how long the consumer backs off next fetch attempt. When the pre-fetch queue has exceeded its queuing thresholds: queued.min.messages and queued.max.messages.kbytes it backs off for 1 seconds. If those parameters have to be set too high to hold 1 s of data, this new parameter allows to back off the fetch earlier, reducing memory requirements.

Fixes

General fixes

• Fix a bug that happens when skipping tags, causing buffer underflow in MetadataResponse. This is triggered since RPC version 9 (v2.1.0), when using Confluent Platform, only when racks are set, observers are activated and there is more than one partition. Fixed by skipping the correct amount of bytes when tags are received.
• Avoid treating an OpenSSL error as a permanent error and treat unclean SSL closes as normal ones. When SSL connections are closed without close_notify, in OpenSSL 3.x a new type of error is set and it was interpreted as permanent in librdkafka. It can cause a different issue depending on the RPC. If received when waiting for OffsetForLeaderEpoch response, it triggers an offset reset following the configured policy. Solved by treating SSL errors as transport errors and by setting an OpenSSL flag that allows to treat unclean SSL closes as normal ones. These types of errors can happen it the other side doesn't support close_notify or if there's a TCP connection reset.

Consumer fixes

• In case of multiple owners of a partition with different generations, the sticky assignor would pick the earliest (lowest generation) member as the current owner, which would lead to stickiness violations. Fixed by choosing the latest (highest generation) member.
• In case where the same partition is owned by two members with the same generation, it indicates an issue. The sticky assignor had some code to handle this, but it was non-functional, and did not have parity with the Java assignor. Fixed by invalidating any such partition from the current assignment completely.

Checksums

Release asset checksums: * v2.2.0.zip SHA256 e9a99476dd326089ce986afd3a5b069ef8b93dbb845bc5157b3d94894de53567 * v2.2.0.tar.gz SHA256 af9a820cbecbc64115629471df7c7cecd40403b6c34bfdbb9223152677a47226

2.1.1 (2023-05-02)

librdkafka v2.1.1 is a maintenance release:

• Avoid duplicate messages when a fetch response is received in the middle of an offset validation request (#4261).
• Fix segmentation fault when subscribing to a non-existent topic and calling rd_kafka_message_leader_epoch() on the polled rkmessage (#4245).
• Fix a segmentation fault when fetching from follower and the partition lease expires while waiting for the result of a list offsets operation (#4254).
• Fix documentation for the admin request timeout, incorrectly stating -1 for infinite timeout. That timeout can't be infinite.
• Fix CMake pkg-config cURL require and use pkg-config Requires.private field (@FantasqueX, @stertingen, #4180).
• Fixes certain cases where polling would not keep the consumer in the group or make it rejoin it (#4256).
• Fix to the C++ set_leader_epoch method of TopicPartitionImpl, that wasn't storing the passed value (@pavel-pimenov, #4267).

Fixes

Consumer fixes

• Duplicate messages can be emitted when a fetch response is received in the middle of an offset validation request. Solved by avoiding a restart from last application offset when offset validation succeeds.
• When fetching from follower, if the partition lease expires after 5 minutes, and a list offsets operation was requested to retrieve the earliest or latest offset, it resulted in segmentation fault. This was fixed by allowing threads different from the main one to call the rd_kafka_toppar_set_fetch_state function, given they hold the lock on the rktp.
• In v2.1.0, a bug was fixed which caused polling any queue to reset the max.poll.interval.ms. Only certain functions were made to reset the timer, but it is possible for the user to obtain the queue with messages from the broker, skipping these functions. This was fixed by encoding information in a queue itself, that, whether polling, resets the timer.

Checksums

Release asset checksums: * v2.1.1.zip SHA256 3b8a59f71e22a8070e0ae7a6b7ad7e90d39da8fddc41ce6c5d596ee7f5a4be4b * v2.1.1.tar.gz SHA256 7be1fc37ab10ebdc037d5c5a9b35b48931edafffae054b488faaff99e60e0108

2.1.0 (2023-04-06)

librdkafka v2.1.0 is a feature release:

• KIP-320 Allow fetchers to detect and handle log truncation (#4122).
• Fix a reference count issue blocking the consumer from closing (#4187).
• Fix a protocol issue with ListGroups API, where an extra field was appended for API Versions greater than or equal to 3 (#4207).
• Fix an issue with max.poll.interval.ms, where polling any queue would cause the timeout to be reset (#4176).
• Fix seek partition timeout, was one thousand times lower than the passed value (#4230).
• Fix multiple inconsistent behaviour in batch APIs during pause or resume operations (#4208). See Consumer fixes section below for more information.
• Update lz4.c from upstream. Fixes CVE-2021-3520 (by @filimonov, #4232).
• Upgrade OpenSSL to v3.0.8 with various security fixes, check the release notes (#4215).

Enhancements

• Added rd_kafka_topic_partition_get_leader_epoch() (and set..()).
• Added partition leader epoch APIs:
• rd_kafka_topic_partition_get_leader_epoch() (and set..())
• rd_kafka_message_leader_epoch()
• rd_kafka_*assign() and rd_kafka_seek_partitions() now supports partitions with a leader epoch set.
• rd_kafka_offsets_for_times() will return per-partition leader-epochs.
• leader_epoch, stored_leader_epoch, and committed_leader_epoch added to per-partition statistics.

Fixes

OpenSSL fixes

• Fixed OpenSSL static build not able to use external modules like FIPS provider module.

Consumer fixes

• A reference count issue was blocking the consumer from closing. The problem would happen when a partition is lost, because forcibly unassigned from the consumer or if the corresponding topic is deleted.
• When using rd_kafka_seek_partitions, the remaining timeout was converted from microseconds to milliseconds but the expected unit for that parameter is microseconds.
• Fixed known issues related to Batch Consume APIs mentioned in v2.0.0 release notes.
• Fixed rd_kafka_consume_batch() and rd_kafka_consume_batch_queue() intermittently updating app_offset and store_offset incorrectly when pause or resume was being used for a partition.
• Fixed rd_kafka_consume_batch() and rd_kafka_consume_batch_queue() intermittently skipping offsets when pause or resume was being used for a partition.

Known Issues

Consume Batch API

• When rd_kafka_consume_batch() and rd_kafka_consume_batch_queue() APIs are used with any of the seek, pause, resume or rebalancing operation, on_consume interceptors might be called incorrectly (maybe multiple times) for not consumed messages.

Consume API

• Duplicate messages can be emitted when a fetch response is received in the middle of an offset validation request.
• Segmentation fault when subscribing to a non-existent topic and calling rd_kafka_message_leader_epoch() on the polled rkmessage.

Checksums

Release asset checksums: * v2.1.0.zip SHA256 2fe898f9f5e2b287d26c5f929c600e2772403a594a691e0560a2a1f2706edf57 * v2.1.0.tar.gz SHA256 d8e76c4b1cde99e283a19868feaaff5778aa5c6f35790036c5ef44bc5b5187aa

2.0.2 (2023-01-20)

librdkafka v2.0.2 is a bugfix release:

• Fix OpenSSL version in Win32 nuget package (#4152).

Checksums

Release asset checksums: * v2.0.2.zip SHA256 87010c722111539dc3c258a6be0c03b2d6d4a607168b65992eb0076c647e4e9d * v2.0.2.tar.gz SHA256 f321bcb1e015a34114c83cf1aa7b99ee260236aab096b85c003170c90a47ca9d

2.0.1 (2023-01-19)

librdkafka v2.0.1 is a bugfix release:

• Fixed nuget package for Linux ARM64 release (#4150).

Checksums

Release asset checksums: * v2.0.1.zip SHA256 7121df3fad1f72ea1c42dcc4e5367337207a75966216c63e58222c6433c528e0 * v2.0.1.tar.gz SHA256 3670f8d522e77f79f9d09a22387297ab58d1156b22de12ef96e58b7d57fca139

2.0.0 (2023-01-18)

librdkafka v2.0.0 is a feature release:

• KIP-88 OffsetFetch Protocol Update (#3995).
• KIP-222 Add Consumer Group operations to Admin API (started by @lesterfan, #3995).
• KIP-518 Allow listing consumer groups per state (#3995).
• KIP-396 Partially implemented: support for AlterConsumerGroupOffsets (started by @lesterfan, #3995).
• OpenSSL 3.0.x support - the maximum bundled OpenSSL version is now 3.0.7 (previously 1.1.1q).
• Fixes to the transactional and idempotent producer.

Upgrade considerations

OpenSSL 3.0.x

OpenSSL default ciphers

The introduction of OpenSSL 3.0.x in the self-contained librdkafka bundles changes the default set of available ciphers, in particular all obsolete or insecure ciphers and algorithms as listed in the OpenSSL legacy manual page are now disabled by default.

WARNING: These ciphers are disabled for security reasons and it is highly recommended NOT to use them.

Should you need to use any of these old ciphers you'll need to explicitly enable the legacy provider by configuring ssl.providers=default,legacy on the librdkafka client.

OpenSSL engines and providers

OpenSSL 3.0.x deprecates the use of engines, which is being replaced by providers. As such librdkafka will emit a deprecation warning if ssl.engine.location is configured.

OpenSSL providers may be configured with the new ssl.providers configuration property.

Broker TLS certificate hostname verification

The default value for ssl.endpoint.identification.algorithm has been changed from none (no hostname verification) to https, which enables broker hostname verification (to counter man-in-the-middle impersonation attacks) by default.

To restore the previous behaviour, set ssl.endpoint.identification.algorithm to none.

Known Issues

Poor Consumer batch API messaging guarantees

The Consumer Batch APIs rd_kafka_consume_batch() and rd_kafka_consume_batch_queue() are not thread safe if rkmessages_size is greater than 1 and any of the seek, pause, resume or rebalancing operation is performed in parallel with any of the above APIs. Some of the messages might be lost, or erroneously returned to the application, in the above scenario.

It is strongly recommended to use the Consumer Batch APIs and the mentioned operations in sequential order in order to get consistent result.

For rebalancing operation to work in sequencial manner, please set rebalance_cb configuration property (refer examples/rdkafka_complex_consumer_example.c for the help with the usage) for the consumer.

Enhancements

• Self-contained static libraries can now be built on Linux arm64 (#4005).
• Updated to zlib 1.2.13, zstd 1.5.2, and curl 7.86.0 in self-contained librdkafka bundles.
• Added on_broker_state_change() interceptor
• The C++ API no longer returns strings by const value, which enables better move optimization in callers.
• Added rd_kafka_sasl_set_credentials() API to update SASL credentials.
• Setting allow.auto.create.topics will no longer give a warning if used by a producer, since that is an expected use case. Improvement in documentation for this property.
• Added a resolve_cb configuration setting that permits using custom DNS resolution logic.
• Added rd_kafka_mock_broker_error_stack_cnt().
• The librdkafka.redist NuGet package has been updated to have fewer external dependencies for its bundled librdkafka builds, as everything but cyrus-sasl is now built-in. There are bundled builds with and without linking to cyrus-sasl for maximum compatibility.
• Admin API DescribeGroups() now provides the group instance id for static members KIP-345 (#3995).

Fixes

General fixes

• Windows: couldn't read a PKCS#12 keystore correctly because binary mode wasn't explicitly set and Windows defaults to text mode.
• Fixed memory leak when loading SSL certificates (@Mekk, #3930)
• Load all CA certificates from ssl.ca.pem, not just the first one.
• Each HTTP request made when using OAUTHBEARER OIDC would leak a small amount of memory.

Transactional producer fixes

• When a PID epoch bump is requested and the producer is waiting to reconnect to the transaction coordinator, a failure in a find coordinator request could cause an assert to fail. This is fixed by retrying when the coordinator is known (#4020).
• Transactional APIs (except send_offsets_for_transaction()) that timeout due to low timeout_ms may now be resumed by calling the same API again, as the operation continues in the background.
• For fatal idempotent producer errors that may be recovered by bumping the epoch the current transaction must first be aborted prior to the epoch bump. This is now handled correctly, which fixes issues seen with fenced transactional producers on fatal idempotency errors.
• Timeouts for EndTxn requests (transaction commits and aborts) are now automatically retried and the error raised to the application is also a retriable error.
• TxnOffsetCommitRequests were retried immediately upon temporary errors in send_offsets_to_transactions(), causing excessive network requests. These retries are now delayed 500ms.
• If init_transactions() is called with an infinite timeout (-1), the timeout will be limited to 2 * transaction.timeout.ms. The application may retry and resume the call if a retriable error is returned.

Consumer fixes

• Back-off and retry JoinGroup request if coordinator load is in progress.
• Fix rd_kafka_consume_batch() and rd_kafka_consume_batch_queue() skipping other partitions' offsets intermittently when seek, pause, resume or rebalancing is used for a partition.
• Fix rd_kafka_consume_batch() and rd_kafka_consume_batch_queue() intermittently returing incorrect partitions' messages if rebalancing happens during these operations.

Checksums

Release asset checksums: * v2.0.0.zip SHA256 9d8a8be30ed09daf6c560f402e91db22fcaea11cac18a0d3c0afdbf884df1d4e * v2.0.0.tar.gz SHA256 f75de3545b3c6cc027306e2df0371aefe1bb8f86d4ec612ed4ebf7bfb2f817cd

1.9.2 (2022-08-01)

librdkafka v1.9.2 is a maintenance release:

• The SASL OAUTHBEAR OIDC POST field was sometimes truncated by one byte (#3192).
• The bundled version of OpenSSL has been upgraded to version 1.1.1q for non-Windows builds. Windows builds remain on OpenSSL 1.1.1n for the time being.
• The bundled version of Curl has been upgraded to version 7.84.0.

Checksums

Release asset checksums: * v1.9.2.zip SHA256 4ecb0a3103022a7cab308e9fecd88237150901fa29980c99344218a84f497b86 * v1.9.2.tar.gz SHA256 3fba157a9f80a0889c982acdd44608be8a46142270a389008b22d921be1198ad

1.9.1 (2022-07-06)

librdkafka v1.9.1

librdkafka v1.9.1 is a maintenance release:

• The librdkafka.redist NuGet package now contains OSX M1/arm64 builds.
• Self-contained static libraries can now be built on OSX M1 too, thanks to disabling curl's configure runtime check.

Checksums

Release asset checksums: * v1.9.1.zip SHA256 d3fc2e0bc00c3df2c37c5389c206912842cca3f97dd91a7a97bc0f4fc69f94ce * v1.9.1.tar.gz SHA256 3a54cf375218977b7af4716ed9738378e37fe400a6c5ddb9d622354ca31fdc79

1.9.0 (2022-06-16)

librdkafka v1.9.0

librdkafka v1.9.0 is a feature release:

• Added KIP-768 OUATHBEARER OIDC support (by @jliunyu, #3560)
• Added KIP-140 Admin API ACL support (by @emasab, #2676)

Upgrade considerations

• Consumer: rd_kafka_offsets_store() (et.al) will now return an error for any partition that is not currently assigned (through rd_kafka_*assign()). This prevents a race condition where an application would store offsets after the assigned partitions had been revoked (which resets the stored offset), that could cause these old stored offsets to be committed later when the same partitions were assigned to this consumer again - effectively overwriting any committed offsets by any consumers that were assigned the same partitions previously. This would typically result in the offsets rewinding and messages to be reprocessed. As an extra effort to avoid this situation the stored offset is now also reset when partitions are assigned (through rd_kafka_*assign()). Applications that explicitly call ..offset*_store() will now need to handle the case where RD_KAFKA_RESP_ERR__STATE is returned in the per-partition .err field - meaning the partition is no longer assigned to this consumer and the offset could not be stored for commit.

Enhancements

• Improved producer queue scheduling. Fixes the performance regression introduced in v1.7.0 for some produce patterns. (#3538, #2912)
• Windows: Added native Win32 IO/Queue scheduling. This removes the internal TCP loopback connections that were previously used for timely queue wakeups.
• Added socket.connection.setup.timeout.ms (default 30s). The maximum time allowed for broker connection setups (TCP connection as well as SSL and SASL handshakes) is now limited to this value. This fixes the issue with stalled broker connections in the case of network or load balancer problems. The Java clients has an exponential backoff to this timeout which is limited by socket.connection.setup.timeout.max.ms - this was not implemented in librdkafka due to differences in connection handling and ERR__ALL_BROKERS_DOWN error reporting. Having a lower initial connection setup timeout and then increase the timeout for the next attempt would yield possibly false-positive ERR__ALL_BROKERS_DOWN too early.
• SASL OAUTHBEARER refresh callbacks can now be scheduled for execution on librdkafka's background thread. This solves the problem where an application has a custom SASL OAUTHBEARER refresh callback and thus needs to call rd_kafka_poll() (et.al.) at least once to trigger the refresh callback before being able to connect to brokers. With the new rd_kafka_conf_enable_sasl_queue() configuration API and rd_kafka_sasl_background_callbacks_enable() the refresh callbacks can now be triggered automatically on the librdkafka background thread.
• rd_kafka_queue_get_background() now creates the background thread if not already created.
• Added rd_kafka_consumer_close_queue() and rd_kafka_consumer_closed(). This allow applications and language bindings to implement asynchronous consumer close.
• Bundled zlib upgraded to version 1.2.12.
• Bundled OpenSSL upgraded to 1.1.1n.
• Added test.mock.broker.rtt to simulate RTT/latency for mock brokers.

Fixes

General fixes

• Fix various 1 second delays due to internal broker threads blocking on IO even though there are events to handle. These delays could be seen randomly in any of the non produce/consume request APIs, such as commit_transaction(), list_groups(), etc.
• Windows: some applications would crash with an error message like no OPENSSL_Applink() written to the console if ssl.keystore.location was configured. This regression was introduced in v1.8.0 due to use of vcpkgs and how keystore file was read. #3554.
• Windows 32-bit only: 64-bit atomic reads were in fact not atomic and could in rare circumstances yield incorrect values. One manifestation of this issue was the max.poll.interval.ms consumer timer expiring even though the application was polling according to profile. Fixed by @WhiteWind (#3815).
• rd_kafka_clusterid() would previously fail with timeout if called on cluster with no visible topics (#3620). The clusterid is now returned as soon as metadata has been retrieved.
• Fix hang in rd_kafka_list_groups() if there are no available brokers to connect to (#3705).
• Millisecond timeouts (timeout_ms) in various APIs, such as rd_kafka_poll(), was limited to roughly 36 hours before wrapping. (#3034)
• If a metadata request triggered by rd_kafka_metadata() or consumer group rebalancing encountered a non-retriable error it would not be propagated to the caller and thus cause a stall or timeout, this has now been fixed. (@aiquestion, #3625)
• AdminAPI DeleteGroups() and DeleteConsumerGroupOffsets(): if the given coordinator connection was not up by the time these calls were initiated and the first connection attempt failed then no further connection attempts were performed, ulimately leading to the calls timing out. This is now fixed by keep retrying to connect to the group coordinator until the connection is successful or the call times out. Additionally, the coordinator will be now re-queried once per second until the coordinator comes up or the call times out, to detect change in coordinators.
• Mock cluster rd_kafka_mock_broker_set_down() would previously accept and then disconnect new connections, it now refuses new connections.

Consumer fixes

• rd_kafka_offsets_store() (et.al) will now return an error for any partition that is not currently assigned (through rd_kafka_*assign()). See Upgrade considerations above for more information.
• rd_kafka_*assign() will now reset/clear the stored offset. See Upgrade considerations above for more information.
• seek() followed by pause() would overwrite the seeked offset when later calling resume(). This is now fixed. (#3471). Note: Avoid storing offsets (offsets_store()) after calling seek() as this may later interfere with resuming a paused partition, instead store offsets prior to calling seek.
• A ERR_MSG_SIZE_TOO_LARGE consumer error would previously be raised if the consumer received a maximum sized FetchResponse only containing (transaction) aborted messages with no control messages. The fetching did not stop, but some applications would terminate upon receiving this error. No error is now raised in this case. (#2993) Thanks to @jacobmikesell for providing an application to reproduce the issue.
• The consumer no longer backs off the next fetch request (default 500ms) when the parsed fetch response is truncated (which is a valid case). This should speed up the message fetch rate in case of maximum sized fetch responses.
• Fix consumer crash (assert: rkbuf->rkbuf_rkb) when parsing malformed JoinGroupResponse consumer group metadata state.
• Fix crash (cant handle op type) when using consume_batch_queue() (et.al) and an OAUTHBEARER refresh callback was set. The callback is now triggered by the consume call. (#3263)
• Fix partition.assignment.strategy ordering when multiple strategies are configured. If there is more than one eligible strategy, preference is determined by the configured order of strategies. The partitions are assigned to group members according to the strategy order preference now. (#3818)
• Any form of unassign*() (absolute or incremental) is now allowed during consumer close rebalancing and they're all treated as absolute unassigns. (@kevinconaway)

Transactional producer fixes

• Fix message loss in idempotent/transactional producer. A corner case has been identified that may cause idempotent/transactional messages to be lost despite being reported as successfully delivered: During cluster instability a restarting broker may report existing topics as non-existent for some time before it is able to acquire up to date cluster and topic metadata. If an idempotent/transactional producer updates its topic metadata cache from such a broker the producer will consider the topic to be removed from the cluster and thus remove its local partition objects for the given topic. This also removes the internal message sequence number counter for the given partitions. If the producer later receives proper topic metadata for the cluster the previously "removed" topics will be rediscovered and new partition objects will be created in the producer. These new partition objects, with no knowledge of previous incarnations, would start counting partition messages at zero again. If new messages were produced for these partitions by the same producer instance, the same message sequence numbers would be sent to the broker. If the broker still maintains state for the producer's PID and Epoch it could deem that these messages with reused sequence numbers had already been written to the log and treat them as legit duplicates. This would seem to the producer that these new messages were successfully written to the partition log by the broker when they were in fact discarded as duplicates, leading to silent message loss. The fix included in this release is to save the per-partition idempotency state when a partition is removed, and then recover and use that saved state if the partition comes back at a later time.
• The transactional producer would retry (re)initializing its PID if a PRODUCER_FENCED error was returned from the broker (added in Apache Kafka 2.8), which could cause the producer to seemingly hang. This error code is now correctly handled by raising a fatal error.
• If the given group coordinator connection was not up by the time send_offsets_to_transactions() was called, and the first connection attempt failed then no further connection attempts were performed, ulimately leading to send_offsets_to_transactions() timing out, and possibly also the transaction timing out on the transaction coordinator. This is now fixed by keep retrying to connect to the group coordinator until the connection is successful or the call times out. Additionally, the coordinator will be now re-queried once per second until the coordinator comes up or the call times out, to detect change in coordinators.

Producer fixes

• Improved producer queue wakeup scheduling. This should significantly decrease the number of wakeups and thus syscalls for high message rate producers. (#3538, #2912)
• The logic for enforcing that message.timeout.ms is greather than an explicitly configured linger.ms was incorrect and instead of erroring out early the lingering time was automatically adjusted to the message timeout, ignoring the configured linger.ms. This has now been fixed so that an error is returned when instantiating the producer. Thanks to @larry-cdn77 for analysis and test-cases. (#3709)

Checksums

Release asset checksums: * v1.9.0.zip SHA256 a2d124cfb2937ec5efc8f85123dbcfeba177fb778762da506bfc5a9665ed9e57 * v1.9.0.tar.gz SHA256 59b6088b69ca6cf278c3f9de5cd6b7f3fd604212cd1c59870bc531c54147e889

1.6.2 (2021-11-25)

librdkafka v1.6.2

librdkafka v1.6.2 is a maintenance release with the following backported fixes:

• Upon quick repeated leader changes the transactional producer could receive an OUT_OF_ORDER_SEQUENCE error from the broker, which triggered an Epoch bump on the producer resulting in an InitProducerIdRequest being sent to the transaction coordinator in the middle of a transaction. This request would start a new transaction on the coordinator, but the producer would still think (erroneously) it was in the current transaction. Any messages produced in the current transaction prior to this event would be silently lost when the application committed the transaction, leading to message loss. To avoid message loss a fatal error is now raised. This fix is specific to v1.6.x. librdkafka v1.8.x implements a recoverable error state instead. #3575.
• The transactional producer could stall during a transaction if the transaction coordinator changed while adding offsets to the transaction (send_offsets_to_transaction()). This stall lasted until the coordinator connection went down, the transaction timed out, transaction was aborted, or messages were produced to a new partition, whichever came first. #3571.
• librdkafka's internal timers would not start if the timeout was set to 0, which would result in some timeout operations not being enforced correctly, e.g., the transactional producer API timeouts. These timers are now started with a timeout of 1 microsecond.
• Force address resolution if the broker epoch changes (#3238).

Checksums

Release asset checksums: * v1.6.2.zip SHA256 1d389a98bda374483a7b08ff5ff39708f5a923e5add88b80b71b078cb2d0c92e * v1.6.2.tar.gz SHA256 b9be26c632265a7db2fdd5ab439f2583d14be08ab44dc2e33138323af60c39db

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Last modified: 2026-06-30 21:44:44