Matthias created FLINK-24147:
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Summary: HDFS lease issues on Flink retry
Key: FLINK-24147
URL: https://issues.apache.org/jira/browse/FLINK-24147
Project: Flink
Issue Type: Bug
Components: Connectors / Hadoop Compatibility
Affects Versions: 1.13.2, 1.12.5, 1.14.0
Reporter: Matthias
This issue was brought up on the [ML thread "hdfs lease issues on flink
retry"|https://lists.apache.org/x/thread.html/r9e5dc9cbd0a41b88565bd6c8c1c9d864ffdd343b4a96bd4dd0dd8a97@%3Cuser.flink.apache.org%3E].
See attached jobmanager.log which was provided by the user.
The user ran into {{FileAlreadyExistsException}} when it tried to create a file
for which a lease already existed. [~dmvk] helped investigating this.
The problem seems to be that we use a fixed retry id {{0}} in
[HadoopOutputFormatBase:137|https://github.com/apache/flink/blob/c6997c97c575d334679915c328792b8a3067cfb5/flink-connectors/flink-hadoop-compatibility/src/main/java/org/apache/flink/api/java/hadoop/mapred/HadoopOutputFormatBase.java#L137].
Each resource in HDFS is allowed to have only one Writer accessing it. The
LeaseManager manages this through leases. It appears that we tried to access
the same file through another task due to {{HadoopOutputFormatBase}} generating
the same {{TaskAttemptId}}. The retry interval was shorter (in that case 10
seconds) than Hadoop's hard-coded soft lease limit of 1min (see
[hadoop:HdfsConstants:62|https://github.com/apache/hadoop/blob/a9c1489e31e8f602de62bd3ecc517aa6597ab2f8/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/protocol/HdfsConstants.java#L62]).
We could be able to overcome this by adding a dynamic retry count instead of
{{_0}}.
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