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