github.com/IBM/sarama

New Features:

• The client now tracks consumer group coordinators using ConsumerMetadataRequests similar to how it tracks partition leadership using regular MetadataRequests (#411). This adds two methods to the client API:
  • Coordinator(consumerGroup string) (*Broker, error)
  • RefreshCoordinator(consumerGroup string) error

Improvements:

• ConsumerMetadataResponses now automatically create a Broker object out of the ID/address/port combination for the Coordinator; accessing the fields individually has been deprecated (#413).
• Much improved handling of OffsetOutOfRange errors in the consumer. Consumers will fail to start if the provided offset is out of range (#418) and they will automatically shut down if the offset falls out of range (#424).
• Small performance improvement in encoding and decoding protocol messages (#427).

Bug Fixes:

• Fix a rare race condition in the client's background metadata refresher if it happens to be activated while the client is being closed (#422).

Improvements:

• The producer's behaviour when Flush.Frequency is set is now more intuitive (#389).
• The producer is now somewhat more memory-efficient during and after retrying messages due to an improved queue implementation (#396).
• The consumer produces much more useful logging output when leadership changes (#385).
• The client's GetOffset method will now automatically refresh metadata and retry once in the event of stale information or similar (#394).
• Broker connections now have support for using TCP keepalives (#407).

Bug Fixes:

• The OffsetCommitRequest message now correctly implements all three possible API versions (#390, #400).

Improvements:

• Wrap the producer's partitioner call in a circuit-breaker so that repeatedly broken topics don't choke throughput (#373).

Bug Fixes:

• Fix the producer's internal reference counting in certain unusual scenarios (#367).
• Fix the consumer's internal reference counting in certain unusual scenarios (#369).
• Fix a condition where the producer's internal control messages could have gotten stuck (#368).
• Fix an issue where invalid partition lists would be cached when asking for metadata for a non-existant topic (#372).

Version 1.0.0 is the first tagged version, and is almost a complete rewrite. The primary differences with previous untagged versions are:

• The producer has been rewritten; there is now a SyncProducer with a blocking API, and an AsyncProducer that is non-blocking.
• The consumer has been rewritten to only open one connection per broker instead of one connection per partition.
• The main types of Sarama are now interfaces to make depedency injection easy; mock implementations for Consumer, SyncProducer and AsyncProducer are provided in the github.com/IBM/sarama/mocks package.
• For most uses cases, it is no longer necessary to open a Client; this will be done for you.
• All the configuration values have been unified in the Config struct.
• Much improved test suite.