[jira] [Created] (KAFKA-7143) Cannot use KafkaConsumer with Kotlin coroutines due to Thread id check

["Raman Gupta (JIRA)" <ji...@apache.org>]

Raman Gupta created KAFKA-7143:
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             Summary: Cannot use KafkaConsumer with Kotlin coroutines due to Thread id check
                 Key: KAFKA-7143
                 URL: https://issues.apache.org/jira/browse/KAFKA-7143
             Project: Kafka
          Issue Type: Improvement
          Components: clients
    Affects Versions: 1.1.0
            Reporter: Raman Gupta


I am using a new KafkaConsumer via Kotlin. My application makes use of Kotlin [coroutines|https://kotlinlang.org/docs/reference/coroutines.html], which supports a style of async programming that avoids the need for callbacks (and existing callback-based API's such as Kafka's can easily be adapted to this). With coroutines, methods with callbacks are suspended, and resumed once the call is complete. With this approach, while access to the KafkaConsumer is done in a thread-safe way, it does NOT happen from a single thread -- a different underlying thread may actually execute the code after the suspension point.

However, the KafkaConsumer includes additional checks to verify not only the thread safety of the client, but that the *same thread* is being used -- if the same thread (by id) is not being used the consumer throws an exception like:

{code}
Exception in thread "ForkJoinPool.commonPool-worker-25" java.util.ConcurrentModificationException: KafkaConsumer is not safe for multi-threaded access
	at org.apache.kafka.clients.consumer.KafkaConsumer.acquire(KafkaConsumer.java:1824)
	at org.apache.kafka.clients.consumer.KafkaConsumer.acquireAndEnsureOpen(KafkaConsumer.java:1808)
	at org.apache.kafka.clients.consumer.KafkaConsumer.commitAsync(KafkaConsumer.java:1321)
{code}

I understand this check is present to protect people from themselves, but I'd like the ability to disable this check so that this code can be used effectively by libraries such as Kotlin coroutines.



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