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https://issues.apache.org/jira/browse/FLINK-6290?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15962996#comment-15962996
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ASF GitHub Bot commented on FLINK-6290:
---------------------------------------
GitHub user dawidwys opened a pull request:
https://github.com/apache/flink/pull/3706
[FLINK-6290] SharedBuffer is improperly released when multiple edges …
…between entries
Thanks for contributing to Apache Flink. Before you open your pull request,
please take the following check list into consideration.
If your changes take all of the items into account, feel free to open your
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- [ ] General
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- [ ] Documentation
- Documentation has been added for new functionality
- Old documentation affected by the pull request has been updated
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- [ ] Tests & Build
- Functionality added by the pull request is covered by tests
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You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dawidwys/flink cep-sharedbuffer-bug
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/3706.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #3706
----
----
> SharedBuffer is improperly released when multiple edges between entries
> -----------------------------------------------------------------------
>
> Key: FLINK-6290
> URL: https://issues.apache.org/jira/browse/FLINK-6290
> Project: Flink
> Issue Type: Bug
> Components: CEP
> Affects Versions: 1.3.0
> Reporter: Dawid Wysakowicz
> Assignee: Dawid Wysakowicz
> Priority: Critical
> Fix For: 1.3.0
>
>
> Below test right now fails:
> {code}
> @Test
> public void testClearingSharedBufferWithMultipleEdgesBetweenEntries() {
> SharedBuffer<String, Event> sharedBuffer = new
> SharedBuffer<>(Event.createTypeSerializer());
> int numberEvents = 8;
> Event[] events = new Event[numberEvents];
> final long timestamp = 1L;
> for (int i = 0; i < numberEvents; i++) {
> events[i] = new Event(i + 1, "e" + (i + 1), i);
> }
> sharedBuffer.put("start", events[1], timestamp,
> DeweyNumber.fromString("1"));
> sharedBuffer.put("branching", events[2], timestamp, "start",
> events[1], timestamp, DeweyNumber.fromString("1.0"));
> sharedBuffer.put("branching", events[3], timestamp, "start",
> events[1], timestamp, DeweyNumber.fromString("1.1"));
> sharedBuffer.put("branching", events[3], timestamp,
> "branching", events[2], timestamp, DeweyNumber.fromString("1.0.0"));
> sharedBuffer.put("branching", events[4], timestamp,
> "branching", events[3], timestamp, DeweyNumber.fromString("1.0.0.0"));
> sharedBuffer.put("branching", events[4], timestamp,
> "branching", events[3], timestamp, DeweyNumber.fromString("1.1.0"));
> //simulate IGNORE (next event can point to events[2])
> sharedBuffer.lock("branching", events[2], timestamp);
> sharedBuffer.release("branching", events[4], timestamp);
> //There should be still events[1] and events[2] in the buffer
> assertFalse(sharedBuffer.isEmpty());
> }
> {code}
> The problem is with the {{SharedBuffer#internalRemove}} method:
> {code}
> private void internalRemove(final SharedBufferEntry<K, V> entry) {
> Stack<SharedBufferEntry<K, V>> entriesToRemove = new Stack<>();
> entriesToRemove.add(entry);
> while (!entriesToRemove.isEmpty()) {
> SharedBufferEntry<K, V> currentEntry =
> entriesToRemove.pop();
> if (currentEntry.getReferenceCounter() == 0) {
> currentEntry.remove();
> for (SharedBufferEdge<K, V> edge:
> currentEntry.getEdges()) {
> if (edge.getTarget() != null) {
>
> edge.getTarget().decreaseReferenceCounter();
>
> entriesToRemove.push(edge.getTarget());
> }
> }
> }
> }
> }
> {code}
> When currentEntry has multiple edges to the same entry. The entry will be
> added twice to the entriesToRemove and it's edges will be removed twice and
> the second edge can potentially change the referenceCounter for both of those
> entries to 0. Resulting in removing this entry twice.
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