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https://issues.apache.org/jira/browse/GEODE-4704?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Swapnil Bawaskar closed GEODE-4704.
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> GatewaySender batch conflation can incorrectly conflate events causing out of
> order processing
> ----------------------------------------------------------------------------------------------
>
> Key: GEODE-4704
> URL: https://issues.apache.org/jira/browse/GEODE-4704
> Project: Geode
> Issue Type: Bug
> Components: wan
> Reporter: Barry Oglesby
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.5.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> In the current implementation of \{{AbstractGatewaySenderEventProcessor
> conflate}} can incorrectly conflate two create events on the same key.
> The else clause of the conflate method (meaning the event is not conflatable)
> assumes there isn't already a event with the same region, key and operation
> in the map. It just does a put:
> {noformat}
> ConflationKey key = new ConflationKey(gsEvent.getRegion().getFullPath(),
> gsEvent.getKeyToConflate(), gsEvent.getOperation());
> conflatedEventsMap.put(key, gsEvent);
> {noformat}
> In certain cases, there could already be a create event on the same region,
> key and operation in the batch, so the previous one gets replaced by the
> later once which causes the events to be processed out of order.
> These 4 events:
> {noformat}
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=100;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_13964;shadowKey=27709]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=101;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_14024;shadowKey=27822]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=102;bucketId=24];operation=DESTROY;region=/dataStoreRegion;key=Object_13964;shadowKey=27935]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=104;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_14024;shadowKey=28161]
> {noformat}
> Become these 3 events:
> {noformat}
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=100;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_13964;shadowKey=27709]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=104;bucketId=24];operation=CREATE;region=/dataStoreRegion;key=Object_14024;shadowKey=28161]
> SenderEventImpl[id=EventIDid=57bytes;threadID=0x10018|112;sequenceID=102;bucketId=24];operation=DESTROY;region=/dataStoreRegion;key=Object_13964;shadowKey=27935]
> {noformat}
> Notice the shadowKeys and sequenceIds are out of order after the conflation.
> The fix will be to include the shadow key in hashCode and equals in the case
> where the event is not conflatable.
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