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https://issues.apache.org/jira/browse/KAFKA-17103?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18014773#comment-18014773
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Chang-Yu Huang commented on KAFKA-17103:
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Hey [~zzk1] [~girishn] are you still watching for this issue? I want to take it
and already have a solution.
> MockClient tight loops when no metadata is present in KafkaProducerTest
> -----------------------------------------------------------------------
>
> Key: KAFKA-17103
> URL: https://issues.apache.org/jira/browse/KAFKA-17103
> Project: Kafka
> Issue Type: Test
> Components: clients
> Reporter: Greg Harris
> Assignee: zhengke zhou
> Priority: Minor
> Labels: newbie
>
> MockClient can throw this exception:
> {noformat}
> [2024-07-09 13:19:33,574] ERROR [Producer clientId=producer-1] Uncaught error
> in kafka producer I/O thread:
> (org.apache.kafka.clients.producer.internals.Sender:253)
> java.lang.IllegalStateException: No previous metadata update to use
> at
> org.apache.kafka.clients.MockClient$DefaultMockMetadataUpdater.updateWithCurrentMetadata(MockClient.java:700)
> at org.apache.kafka.clients.MockClient.poll(MockClient.java:323)
> at
> org.apache.kafka.clients.producer.internals.Sender.runOnce(Sender.java:349)
> at org.apache.kafka.clients.producer.internals.Sender.run(Sender.java:251)
> at java.base/java.lang.Thread.run(Thread.java:829){noformat}
> This happens whenever the MockClient.DefaultMockMetadataUpdater#lastUpdate
> variable is null, which is the case whenever there has not been any mock
> metadata update.
> In practice, this appears to happen in
> KafkaProducerTest#testTopicExpiryInMetadata,
> KafkaProducerTest#testTopicRefreshInMetadata,
> KafkaProducerTest#testTopicNotExistingInMetadata. These three tests also use
> busy-waiting to have another thread wait for the metadata update request and
> then provide the metadata update.
> We should find some mechanism to allow mocking these metadata updates that
> avoids this busy waiting/tight looping pattern, as it introduces an
> opportunity for nondeterminism and wastes CPU cycles.
> The solution should remove any usage of Thread.sleep/Utils.sleep/Time.SYSTEM.
> Ideally the solution wouldn't require an additional test thread, but this is
> optional.
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