Consumers

• Avoid resending FetchRequests that are pending on internal queue
• Log debug messages when skipping fetched messages due to offset checks
• KAFKA-3013: Include topic-partition in exception for expired batches
• KAFKA-3318: clean up consumer logging and error messages
• Improve unknown coordinator error handling
• Improve auto-commit error handling when group_id is None
• Add paused() API (zackdever PR 602)
• Add default_offset_commit_callback to KafkaConsumer DEFAULT_CONFIGS

Producers

Clients

• Support SSL connections
• Use selectors module for non-blocking IO
• Refactor KafkaClient connection management
• Fix AttributeError in del
• SimpleClient: catch errors thrown by _get_leader_for_partition (zackdever PR 606)

Documentation

• Fix serializer/deserializer examples in README
• Update max.block.ms docstring
• Remove errant next(consumer) from consumer documentation
• Add producer.flush() to usage docs

Internals

• Add initial metrics implementation (zackdever PR 637)
• KAFKA-2136: support Fetch and Produce v1 (throttle_time_ms)
• Use version-indexed lists for request/response protocol structs (dpkp PR 630)
• Split kafka.common into kafka.structs and kafka.errors
• Handle partial socket send() (dpkp PR 611)
• Fix windows support (dpkp PR 603)
• IPv6 support (TimEvens PR 615; Roguelazer PR 642)