Denes Arvay created FLUME-2973:
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Summary: Deadlock in hdfs sink
Key: FLUME-2973
URL: https://issues.apache.org/jira/browse/FLUME-2973
Project: Flume
Issue Type: Bug
Components: Sinks+Sources
Affects Versions: v1.7.0
Reporter: Denes Arvay
Assignee: Denes Arvay
Priority: Critical
Automatic close of BucketWriters (when open file count reached
{{hdfs.maxOpenFiles}}) and the file rolling thread can end up in deadlock.
When creating a new {{BucketWriter}} in {{HDFSEventSink}} it locks
{{HDFSEventSink.sfWritersLock}} and the {{close()}} called in
{{HDFSEventSink.sfWritersLock.removeEldestEntry}} tries to lock the
{{BucketWriter}} instance.
On the other hand if the file is being rolled in
{{BucketWriter.close(boolean)}} it locks the {{BucketWriter}} instance first
and in the close callback it tries to lock the {{sfWritersLock}}.
The chances for this deadlock is higher when the {{hdfs.maxOpenFiles}}'s value
is low (1).
Script to reproduce:
https://gist.github.com/adenes/96503a6e737f9604ab3ee9397a5809ff
(put to
{{flume-ng-sinks/flume-hdfs-sink/src/main/java/org/apache/flume/sink/hdfs}})
Deadlock usually occurs before ~30 iterations.
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