Sebastiaan created KAFKA-8412:
---------------------------------
Summary: Still a nullpointer exception thrown on shutdown while
flushing before closing producers
Key: KAFKA-8412
URL: https://issues.apache.org/jira/browse/KAFKA-8412
Project: Kafka
Issue Type: Bug
Components: streams
Affects Versions: 2.1.1
Reporter: Sebastiaan
I found a closed issue and replied there but decided to open one myself because
although they're related they're slightly different. The original issue is at
https://issues.apache.org/jira/browse/KAFKA-7678
The fix there has been to implement a null check around closing a producer
because in some cases the producer is already null there (has been closed
already)
In version 2.1.1 we are getting a very similar exception, but in the 'flush'
method that is called pre-close. This is in the log:
{code:java}
message: stream-thread
[webhook-poster-7034dbb0-7423-476b-98f3-d18db675d6d6-StreamThread-1] Failed
while closing StreamTask 1_26 due to the following error:
logger_name: org.apache.kafka.streams.processor.internals.AssignedStreamsTasks
java.lang.NullPointerException: null
at
org.apache.kafka.streams.processor.internals.RecordCollectorImpl.flush(RecordCollectorImpl.java:245)
at
org.apache.kafka.streams.processor.internals.StreamTask.flushState(StreamTask.java:493)
at
org.apache.kafka.streams.processor.internals.StreamTask.commit(StreamTask.java:443)
at
org.apache.kafka.streams.processor.internals.StreamTask.suspend(StreamTask.java:568)
at
org.apache.kafka.streams.processor.internals.StreamTask.close(StreamTask.java:691)
at
org.apache.kafka.streams.processor.internals.AssignedTasks.close(AssignedTasks.java:397)
at
org.apache.kafka.streams.processor.internals.TaskManager.shutdown(TaskManager.java:260)
at
org.apache.kafka.streams.processor.internals.StreamThread.completeShutdown(StreamThread.java:1181)
at
org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:758){code}
Followed by:
{code:java}
message: task [1_26] Could not close task due to the following error:
logger_name: org.apache.kafka.streams.processor.internals.StreamTask
java.lang.NullPointerException: null
at
org.apache.kafka.streams.processor.internals.RecordCollectorImpl.flush(RecordCollectorImpl.java:245)
at
org.apache.kafka.streams.processor.internals.StreamTask.flushState(StreamTask.java:493)
at
org.apache.kafka.streams.processor.internals.StreamTask.commit(StreamTask.java:443)
at
org.apache.kafka.streams.processor.internals.StreamTask.suspend(StreamTask.java:568)
at
org.apache.kafka.streams.processor.internals.StreamTask.close(StreamTask.java:691)
at
org.apache.kafka.streams.processor.internals.AssignedTasks.close(AssignedTasks.java:397)
at
org.apache.kafka.streams.processor.internals.TaskManager.shutdown(TaskManager.java:260)
at
org.apache.kafka.streams.processor.internals.StreamThread.completeShutdown(StreamThread.java:1181)
at
org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:758){code}
If I look at the source code at this point, I see a nice null check in the
close method, but not in the flush method that is called just before that:
{code:java}
public void flush() {
this.log.debug("Flushing producer");
this.producer.flush();
this.checkForException();
}
public void close() {
this.log.debug("Closing producer");
if (this.producer != null) {
this.producer.close();
this.producer = null;
}
this.checkForException();
}{code}
Seems to my (ignorant) eye that the flush method should also be wrapped in a
null check in the same way as has been done for close.
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