[
https://issues.apache.org/jira/browse/FLINK-28515?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17569892#comment-17569892
]
Roman Khachatryan commented on FLINK-28515:
-------------------------------------------
Thanks, that would be great [~lijinzhong]
> IIUC, when SubtaskCheckpointCoordinatorImpl handle abort notification, it
> will close all the snapshotIO firstly
Right, SubtaskCheckpointCoordinatorImpl first *tries* to close IO and then
removes the folder.
But when closing the IO, there is a CAS check in AsyncSnapshotCallable.cancel():
{code:java}
protected void cancel() {
closeSnapshotIO();
if (resourceCleanupOwnershipTaken.compareAndSet(false, true)) {
cleanup();
}
}
{code}
So if it's already running, cleanup() can be skipped by the current thread.
closeSnapshotIO() only closes the registry, and I don't see that the folder is
registered with it (Maybe that's a problem?).
Anyways, I think it would be great to have a test to validate the understanding
and the fix.
> The files in local recovery directory hasn't be clean up properly after
> checkpoint abort
> ----------------------------------------------------------------------------------------
>
> Key: FLINK-28515
> URL: https://issues.apache.org/jira/browse/FLINK-28515
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Checkpointing, Runtime / State Backends
> Affects Versions: 1.15.1, 1.16.0
> Reporter: Jinzhong Li
> Assignee: Jinzhong Li
> Priority: Major
> Labels: pull-request-available
> Attachments: C7245668-CE31-4F56-B9CB-12E2F1E900C5.png,
> image-2022-07-19-18-28-20-239.png, image.png
>
>
> In my case, i found that some files in local recovery directory hasn't be
> clean up properly after checkpoint abort(as shown in the attached picture).
> By analyzing flink log, I found that when stateBackend completes the local
> snapshot but the task has not completed the whole snapshot,
> then checkpoint is aborted (caused by checkpoint timeout or netword-error),
> files in the local directory directory may not be cleaned up properly.
> I think the reason for local snapshot file residual is:
> (1) In the org.apache.flink.streaming.runtime.tasks.AsyncCheckpointRunnable,
> the comleted localSnapshot info can be registered into
> org.apache.flink.runtime.state.TaskLocalStateStoreImpl only after task has
> completed the whole snapshot.
> ([AsyncCheckpointRunnable.java#L136|https://github.com/apache/flink/blob/3ec376601f836df6314e771b243ca6f896a7f642/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/AsyncCheckpointRunnable.java#L136]).
> (2) If stateBackend completes the local snapshot but the task has not
> completed the entire snapshot, when checkpoint-aborting is triggered, the
> TaskLocalStateStore can't clean up the unregistered localSnapshot files.
> ([TaskLocalStateStoreImpl.java#L301|https://github.com/apache/flink/blob/3ec376601f836df6314e771b243ca6f896a7f642/flink-runtime/src/main/java/org/apache/flink/runtime/state/TaskLocalStateStoreImpl.java#L301])
> (3) And when SubtaskCheckpointCoordinatorImpl receive the abort notification,
> it will cancel all the ongoing stateSnapshot futureTask in
> 'AsyncCheckpointRunnable.close()'. For rocksdbKeyedStatebackend,
> [AsyncSnapshotTask.cancel
> |https://github.com/apache/flink/blob/dcc9cceab962c897c7a5e55deb868eb2d86468ec/flink-runtime/src/main/java/org/apache/flink/runtime/state/AsyncSnapshotCallable.java#L129]will
> be invoke during checkpoint abort. After this, the
> [RocksDBIncrementalSnapshotOperation.get
> |https://github.com/apache/flink/blob/dcc9cceab962c897c7a5e55deb868eb2d86468ec/flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/snapshot/RocksIncrementalSnapshotStrategy.java#L384]may
> still run until it completes.
> And the localSnapshot files can't be cleaned up in
> RocksDBIncrementalSnapshotOperation.get(finally) and
> AsyncSnapshotCallable.call（[finally-cleanup|https://github.com/apache/flink/blob/dcc9cceab962c897c7a5e55deb868eb2d86468ec/flink-runtime/src/main/java/org/apache/flink/runtime/state/AsyncSnapshotCallable.java#L87]).
> Then the localSnapshot files also can't be cleaned up in
> [AsyncCheckpointRunnable.cleanup|https://github.com/apache/flink/blob/dcc9cceab962c897c7a5e55deb868eb2d86468ec/flink-streaming-java/src/main/java/org/apache/flink/streaming/runtime/tasks/AsyncCheckpointRunnable.java#L391],
> because
> [AsyncSnapshotTask.cancel|https://github.com/apache/flink/blob/dcc9cceab962c897c7a5e55deb868eb2d86468ec/flink-runtime/src/main/java/org/apache/flink/runtime/state/StateUtil.java#L78]
> return ture.
>
> To fix this problem, I think when TaskLocalStateStoreImpl abort Checkpoint,
> we can try to delete the corresponding localRecovery directory, even if the
> checkpoint is not unregistered into TaskLocalStateStoreImpl.
>
>
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
