Ran Tao created FLINK-30334:
-------------------------------
Summary: SourceCoordinator error split check cause HybridSource
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
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 [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 [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/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 than 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
deal with hybrid the other child sources.
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 noreMoreSplit 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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