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