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https://issues.apache.org/jira/browse/FLINK-30334?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhu Zhu closed FLINK-30334.
---------------------------
Resolution: Fixed
master:
6e4e6c68a4a179d932dacafb2771cc84f730bbc0
1.16:
2b5e4ac8df41fe68ae8212eab4a254740e0c5ef4
> SourceCoordinator error splitRequest check cause HybridSource loss of data
> and hang
> -----------------------------------------------------------------------------------
>
> Key: FLINK-30334
> URL: https://issues.apache.org/jira/browse/FLINK-30334
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Coordination
> Affects Versions: 1.16.0, 1.17.0
> Reporter: Ran Tao
> Assignee: Ran Tao
> Priority: Critical
> Labels: pull-request-available
> Fix For: 1.17.0, 1.16.1
>
>
> If we use hybrid source, for example, filesystem source A read a.csv,
> filesystem B read b.csv. It's a very simple case, but it will hang in second
> source with:
> 10802 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.runtime.source.coordinator.SourceCoordinator [] - Source
> Source: hybrid_source[1] received split request from parallel task 0 (#0)
> 10802 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.connector.file.src.impl.StaticFileSplitEnumerator [] -
> Subtask 0 (on host '') is requesting a file source split
> 10803 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.connector.file.src.assigners.LocalityAwareSplitAssigner [] -
> Assigning split to non-localized request: Optional[FileSourceSplit:
> [file:/Users/xxx/a.csv|file:///Users/xxx/a.csv] [0, 49) (no host info)
> ID=0000000001 position=null]
> 10808 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.connector.file.src.impl.StaticFileSplitEnumerator [] -
> Assigned split to subtask 0 : FileSourceSplit:
> [file:/Users/xxx/a.csv|file:///Users/xxx/a.csv] [0, 49) (no host info)
> ID=0000000001 position=null
> 10816 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.hybrid.HybridSourceReader [] - Adding
> splits subtask=0 sourceIndex=0
> currentReader=org.apache.flink.connector.file.src.impl.FileSourceReader@1e8e1971
> [HybridSourceSplit
> {sourceIndex=0, splitId=0000000001}
> ]
> 10817 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.SourceReaderBase [] - Adding
> split(s) to reader: [FileSourceSplit:
> [file:/Users/xxx/a.csv|file:///Users/chucheng/TMP/a.csv] [0, 49) (no host
> info) ID=0000000001 position=null]
> 10822 [Source Data Fetcher for Source: hybrid_source[1] -> Sink: print_out[2]
> (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher [] -
> Starting split fetcher 0
> 10864 [Source Data Fetcher for Source: hybrid_source[1] -> Sink: print_out[2]
> (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher [] -
> Finished reading from splits [0000000001]
> +I[hello_a, flink, 1]
> +I[hello_a, hadoop, 2]
> +I[hello_a, world, 3]
> 10866 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.SourceReaderBase [] - Finished
> reading split(s) [0000000001]
> 10868 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.fetcher.SplitFetcherManager []
> - Closing splitFetcher 0 because it is idle.
> 10868 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher [] -
> Shutting down split fetcher 0
> 10868 [Source Data Fetcher for Source: hybrid_source[1] -> Sink: print_out[2]
> (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.fetcher.SplitFetcher [] - Split
> fetcher 0 exited.
> 10869 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.runtime.source.coordinator.SourceCoordinator [] - Source
> Source: hybrid_source[1] received split request from parallel task 0 (#0)
> 10870 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.connector.file.src.impl.StaticFileSplitEnumerator [] -
> Subtask 0 (on host '') is requesting a file source split
> 10872 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.connector.file.src.impl.StaticFileSplitEnumerator [] - No
> more splits available for subtask 0
> 10872 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.SourceReaderBase [] - Reader
> received NoMoreSplits event.
> 10872 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.hybrid.HybridSourceReader [] - End of
> input subtask=0 sourceIndex=0
> org.apache.flink.connector.file.src.impl.FileSourceReader@1e8e1971
> StaticFileSplitEnumerator:org.apache.flink.connector.file.src.impl.StaticFileSplitEnumerator@69906bb9
> 10874 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.connector.base.source.hybrid.HybridSourceSplitEnumerator []
> - Starting enumerator for sourceIndex=1
> 10879 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.hybrid.HybridSourceReader [] - Switch
> source event: subtask=0 sourceIndex=1
> source=org.apache.flink.connector.file.src.FileSource@12ef574f
> 10879 [Source: hybrid_source[1] -> Sink: print_out[2] (1/1)#0] INFO
> org.apache.flink.connector.base.source.reader.SourceReaderBase [] - Closing
> Source Reader.
> 10882 [SourceCoordinator-Source: hybrid_source[1]] INFO
> org.apache.flink.runtime.source.coordinator.SourceCoordinator [] - Source
> Source: hybrid_source[1] received split request from parallel task 0 (#0)
> *do not read next source data and hang at 'received split request from
> parallel task'*
>
> The reason is that in the 1.16 & master, latest code add
> context.hasNoMoreSplits check then call enumerator.handleSplitRequest. We do
> understand the comments for reducing the call splits. But it not consider the
> the situation about HybridSource. When a subtask hasNoMoreSplits, it will
> switch to next source. But here just set a check without this situation. When
> first source read finish, the context just let this subtask with noMoreSplit
> Status. And the later check can't assign splits with next sources. However ,
> the flink 1.15 is correct.
>
> *SourceCoordinator*
>
> {code:java}
> private void handleRequestSplitEvent(int subtask, int attemptNumber,
> RequestSplitEvent event) {
> LOG.info(
> "Source {} received split request from parallel task {} (#{})",
> operatorName,
> subtask,
> attemptNumber);
> // request splits from the enumerator only if the enumerator has
> un-assigned splits
> // this helps to reduce unnecessary split requests to the enumerator
> if (!context.hasNoMoreSplits(subtask)) {
> enumerator.handleSplitRequest(subtask, event.hostName());
> }
> } {code}
> SourceCoordinator call `context.hasNoMoreSplits` check cause the subtask not
> read the other child sources in hybrid source.
>
> SourceCoordinatorContext
>
> {code:java}
> boolean hasNoMoreSplits(int subtaskIndex) { return
> subtaskHasNoMoreSplits[subtaskIndex]; }
> @Override
> public void signalNoMoreSplits(int subtask) {
> checkSubtaskIndex(subtask);
> // Ensure the split assignment is done by the coordinator executor.
> callInCoordinatorThread(
> () -> {
> subtaskHasNoMoreSplits[subtask] = true;
> signalNoMoreSplitsToAttempts(subtask);
> return null; // void return value
> },
> "Failed to send 'NoMoreSplits' to reader " + subtask);
> }
> {code}
> context set subtask noMoreSplit is true if source is done (without
> considering the hybrid situation).
>
>
> 1.15
>
> {code:java}
> public void handleEventFromOperator(int subtask, OperatorEvent event) {
> runInEventLoop(
> () -> {
> if (event instanceof RequestSplitEvent) {
> LOG.info(
> "Source {} received split request from parallel
> task {}",
> operatorName,
> subtask);
> enumerator.handleSplitRequest(
> subtask, ((RequestSplitEvent) event).hostName());
> } {code}
>
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