librdkafka v1.5.0

The v1.5.0 release brings usability improvements, enhancements and fixes to librdkafka.

Enhancements

• Improved broker connection error reporting with more useful information and hints on the cause of the problem.
• Consumer: Propagate errors when subscribing to unavailable topics (#1540)
• Producer: Add batch.size producer configuration property (#638)
• Add topic.metadata.propagation.max.ms to allow newly manually created topics to be propagated throughout the cluster before reporting them as non-existent. This fixes race issues where CreateTopics() is quickly followed by produce().
• Prefer least idle connection for periodic metadata refreshes, et.al., to allow truly idle connections to time out and to avoid load-balancer-killed idle connection errors (#2845)
• Added rd_kafka_event_debug_contexts() to get the debug contexts for a debug log line (by @wolfchimneyrock).
• Added Test scenarios which define the cluster configuration.
• Added MinGW-w64 builds (@ed-alertedh, #2553)
• ./configure --enable-XYZ now requires the XYZ check to pass, and --disable-XYZ disables the feature altogether (@benesch)
• Added rd_kafka_produceva() which takes an array of produce arguments for situations where the existing rd_kafka_producev() va-arg approach can't be used.
• Added rd_kafka_message_broker_id() to see the broker that a message was produced or fetched from, or an error was associated with.
• Added RTT/delay simulation to mock brokers.

Upgrade considerations

• Subscribing to non-existent and unauthorized topics will now propagate errors RD_KAFKA_RESP_ERR_UNKNOWN_TOPIC_OR_PART and RD_KAFKA_RESP_ERR_TOPIC_AUTHORIZATION_FAILED to the application through the standard consumer error (the err field in the message object).
• Consumer will no longer trigger auto creation of topics, allow.auto.create.topics=true may be used to re-enable the old deprecated functionality.
• The default consumer pre-fetch queue threshold queued.max.messages.kbytes has been decreased from 1GB to 64MB to avoid excessive network usage for low and medium throughput consumer applications. High throughput consumer applications may need to manually set this property to a higher value.
• The default consumer Fetch wait time has been increased from 100ms to 500ms to avoid excessive network usage for low throughput topics.
• If OpenSSL is linked statically, or ssl.ca.location=probe is configured, librdkafka will probe known CA certificate paths and automatically use the first one found. This should alleviate the need to configure ssl.ca.location when the statically linked OpenSSL's OPENSSLDIR differs from the system's CA certificate path.
• The heuristics for handling Apache Kafka < 0.10 brokers has been removed to improve connection error handling for modern Kafka versions. Users on Brokers 0.9.x or older should already be configuring api.version.request=false and broker.version.fallback=... so there should be no functional change.
• The default producer batch accumulation time, linger.ms, has been changed from 0.5ms to 5ms to improve batch sizes and throughput while reducing the per-message protocol overhead. Applications that require lower produce latency than 5ms will need to manually set linger.ms to a lower value.
• librdkafka's build tooling now requires Python 3.x (python3 interpreter).

Fixes

General fixes

• The client could crash in rare circumstances on ApiVersion or SaslHandshake request timeouts (#2326)
• ./configure --LDFLAGS='a=b, c=d' with arguments containing = are now supported (by @sky92zwq).
• ./configure arguments now take precedence over cached configure variables from previous invocation.
• Fix theoretical crash on coord request failure.
• Unknown partition error could be triggered for existing partitions when additional partitions were added to a topic (@benesch, #2915)
• Quickly refresh topic metadata for desired but non-existent partitions. This will speed up the initial discovery delay when new partitions are added to an existing topic (#2917).

Consumer fixes

• The roundrobin partition assignor could crash if subscriptions where asymmetrical (different sets from different members of the group). Thanks to @ankon and @wilmai for identifying the root cause (#2121).
• The consumer assignors could ignore some topics if there were more subscribed topics than consumers in taking part in the assignment.
• The consumer would connect to all partition leaders of a topic even for partitions that were not being consumed (#2826).
• Initial consumer group joins should now be a couple of seconds quicker thanks expedited query intervals (@benesch).
• Fix crash and/or inconsistent subscriptions when using multiple consumers (in the same process) with wildcard topics on Windows.
• Don't propagate temporary offset lookup errors to application.
• Immediately refresh topic metadata when partitions are reassigned to other brokers, avoiding a fetch stall of up to topic.metadata.refresh.interval.ms. (#2955)
• Memory for batches containing control messages would not be freed when using the batch consume APIs (@pf-qiu, #2990).

Producer fixes

• Proper locking for transaction state in EndTxn handler.

Checksums

Release asset checksums:

• v1.5.0.zip SHA256 76a1e83d643405dd1c0e3e62c7872b74e3a96c52be910233e8ec02d501fa33c8
• v1.5.0.tar.gz SHA256 f7fee59fdbf1286ec23ef0b35b2dfb41031c8727c90ced6435b8cf576f23a656