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Posted to commits@pulsar.apache.org by GitBox <gi...@apache.org> on 2022/04/20 09:01:10 UTC

[GitHub] [pulsar] mattisonchao opened a new pull request, #15233: [Fix][Broker] Fix race condition between timeout and completion in `OpAddEntry`

mattisonchao opened a new pull request, #15233:
URL: https://github.com/apache/pulsar/pull/15233

   ### Motivation
   
   In #4455 and #10740, The `OpAddEntry` try to using `opAddEntry.addOpCount` to ensure the `opAddEntry` we got is what we want.(avoid recycle cause race condition)
   
   It seems exists a case causing another race condition. consider the case as follow:
   
   #### Precondition
   
   - We have an `OpAddEntry` that name is A.
   - We got two threads: a timeout check thread and another is a write thread that wants to complete and recycle this `OpAddEntry`.
   - Relative code is as follow(timeout check logic):
   
   https://github.com/apache/pulsar/blob/caf7648653c140c9f922e86425585ab7b5ed3ed6/managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/ManagedLedgerImpl.java#L3825-L3840
   
   #### Race condition process
   
   1. When the timeout checker thread gets `OpAddEntry` A and continues to run until line 3835.
   2. At the same time, the writing thread also gets `OpAddEntry`A, completes and recycles.
   3. At this time, `OpAddEntry`A is taken out of the recycling pool by other threads as `OpAddEntry`B. But at this time the timeout thread has passed the timeout check(line 3834), and `addOpCount` is also obtained from OpAddEntry B, which will cause the `compareAndSet` check to pass.
   
   #### Affect
   
   - The timeout checker will make a new `OpAddEntry` complete timeout.
   
   ### Modifications
   
   - Record `opAddCount` before timeout judgment.
   
   ### Verifying this change
   
   - [x] Make sure that the change passes the CI checks.
   
   ### Documentation
   
   - [x] `no-need-doc` 


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[GitHub] [pulsar] lhotari commented on pull request #15233: [Fix][Broker] Fix race condition between timeout and completion in `OpAddEntry`

Posted by GitBox <gi...@apache.org>.
lhotari commented on PR #15233:
URL: https://github.com/apache/pulsar/pull/15233#issuecomment-1103777395

   Good catch! 
   
   btw. previous revisit to the solution was in #10740


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[GitHub] [pulsar] nicoloboschi commented on pull request #15233: [Fix][Broker] Fix race condition between timeout and completion in `OpAddEntry`

Posted by GitBox <gi...@apache.org>.
nicoloboschi commented on PR #15233:
URL: https://github.com/apache/pulsar/pull/15233#issuecomment-1112117369

   @lhotari this pull must be ported to branch-2.10 also, thanks


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[GitHub] [pulsar] lhotari merged pull request #15233: [Fix][Broker] Fix race condition between timeout and completion in `OpAddEntry`

Posted by GitBox <gi...@apache.org>.
lhotari merged PR #15233:
URL: https://github.com/apache/pulsar/pull/15233


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