[KAFKA-2662] Make ConsumerIterator thread-safe for multiple threads in different Kafka groups

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Auto Closed
• Affects Version/s: 0.8.2.1
• Component/s: consumer
• Assignee: Neha Narkhede
• Reporter: Andrew Pennebaker
• Created: 16/Oct/15 15:56
• Updated: 30/Oct/17 11:52
• Resolved: 30/Oct/17 11:52

Description

The API for obtaining a ConsumerIterator requires a group parameter, implying that ConsumerIterators are thread-safe, as long as each thread is in a different Kafka group. However, in practice, attempting to call hasNext() on ConsumerIterators for a thread in one group, and for a thread in another group, results in an InvalidStateException.

In the future, can we please make ConsumerIterator thread-safe, for a common use case of one consumer thread per group?