Thawan Kooburat created ZOOKEEPER-1624:
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Summary: PrepRequestProcessor abort multi-operation incorrectly
Key: ZOOKEEPER-1624
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1624
Project: ZooKeeper
Issue Type: Bug
Components: server
Reporter: Thawan Kooburat
Priority: Critical
We found this issue when trying to issue multiple instances of the following
multi-op concurrently
multi {
1. create sequential node /a-
2. create node /b
}
The expected result is that only the first multi-op request should success and
the rest of request should fail because /b is already exist
However, the reported result is that the subsequence multi-op failed because of
sequential node creation failed which is not possible.
Below is the return code for each sub-op when issuing 3 instances of the above
multi-op asynchronously
1. ZOK, ZOK
2. ZOK, ZNODEEXISTS,
3. ZNODEEXISTS, ZRUNTIMEINCONSISTENCY,
When I added more debug log. The cause is that PrepRequestProcessor rollback
outstandingChanges of the second multi-op incorrectly causing sequential node
name generation to be incorrect. Below is the sequential node name generated by
PrepRequestProcessor
1. create /a-0001
2. create /a-0003
3. create /a-0001
The bug is getPendingChanges() method. In failed to copied ChangeRecord for the
parent node (/). So rollbackPendingChanges() cannot restore the right previous
change record of the parent node when aborting the second multi-op
The impact of this bug is that sequential node creation on the same parent node
may fail until the previous one is committed. I am not sure if there is other
implication or not.
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