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https://issues.apache.org/jira/browse/ZOOKEEPER-1624?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Thawan Kooburat updated ZOOKEEPER-1624:
---------------------------------------

    Description: 
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.  


  was:
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.  


    
> 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
>            Assignee: Thawan Kooburat
>            Priority: Critical
>         Attachments: ZOOKEEPER-1624.patch
>
>
> 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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