Lu Niu created FLINK-16931:
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Summary: Large _metadata file lead to JobManager not responding
when restart
Key: FLINK-16931
URL: https://issues.apache.org/jira/browse/FLINK-16931
Project: Flink
Issue Type: Bug
Reporter: Lu Niu
When _metadata file is big, JobManager could never recover from checkpoint. It
fall into a loop that fetch checkpoint -> JM timeout -> restart). Here is
related log:
2020-04-01 17:08:25,689 INFO
org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore -
Recovering checkpoints from ZooKeeper.
2020-04-01 17:08:25,698 INFO
org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore - Found
3 checkpoints in ZooKeeper.
2020-04-01 17:08:25,698 INFO
org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore - Trying
to fetch 3 checkpoints from storage.
2020-04-01 17:08:25,698 INFO
org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore - Trying
to retrieve checkpoint 50.
2020-04-01 17:08:48,589 INFO
org.apache.flink.runtime.checkpoint.ZooKeeperCompletedCheckpointStore - Trying
to retrieve checkpoint 51.
2020-04-01 17:09:12,775 INFO org.apache.flink.yarn.YarnResourceManager
- The heartbeat of JobManager with id
02500708baf0bb976891c391afd3d7d5 timed out.
Digging into the code, looks like ExecutionGraph::restart runs in JobMaster
main thread and finally calls
ZooKeeperCompletedCheckpointStore::retrieveCompletedCheckpoint which download
file form DFS. The main thread is basically blocked for a while because of
this. One possible solution is to making the downloading part async. More
things might need to consider as the original change tries to make it
single-threaded. [https://github.com/apache/flink/pull/7568]
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