Greg Harris created KAFKA-17103:
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Summary: 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
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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