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fix:deadlock when reentrant exclusive lock #2905 #2879 #2961

Merged
merged 3 commits into from
Sep 13, 2024
Merged

fix:deadlock when reentrant exclusive lock #2905 #2879 #2961

merged 3 commits into from
Sep 13, 2024

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Roiocam
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@Roiocam Roiocam commented Aug 16, 2024 •
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Motivation

Resolves: #2905 #2879

Investigation

Both of issues point to this stack trace. I have reproduced this with the sample in #2905.

After some investigation, I figured why, because the thread that holds the shared lock also requires exclusive lock in the same time.(I think it happened on error handling, or the channel was disactive when writer was writing).

      at io.lettuce.core.protocol.Sharedlock.lockWritersExclusive(SharedLock.java:139)
      at io.lettuce.core.protocol.SharedLock.doexclusive(SharedLock.java:114)
      at io.lettuce.core.protocol.DefaultEndpoint.doExclusive(DefaultEndpoint.java:741)

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@Roiocam Roiocam marked this pull request as draft August 16, 2024 06:44
@Roiocam Roiocam marked this pull request as ready for review August 16, 2024 07:58
@Roiocam Roiocam changed the title fix:Deadlock when reentrant exclusive lock #2905 fix:Deadlock when reentrant exclusive lock #2905 #2879 Aug 16, 2024
@Roiocam Roiocam changed the title fix:Deadlock when reentrant exclusive lock #2905 #2879 fix:deadlock when reentrant exclusive lock #2905 #2879 Aug 16, 2024
tishun
tishun requested changes Aug 30, 2024
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I agree that this is the most likely culprit as the logic seems to assume the same thread could not be a writer at the moment of attempting to do exclusive operations. I have a few minor suggestions for the change.

src/main/java/io/lettuce/core/protocol/SharedLock.java Outdated Show resolved Hide resolved
src/main/java/io/lettuce/core/protocol/SharedLock.java Outdated Show resolved Hide resolved
@tishun tishun added the status: waiting-for-feedback We need additional information before we can continue label Aug 30, 2024
@tishun tishun removed the status: waiting-for-feedback We need additional information before we can continue label Sep 13, 2024
tishun
tishun approved these changes Sep 13, 2024
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Awesome, thanks for the contibution!

@tishun tishun merged commit bc84058 into redis:main Sep 13, 2024
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@tishun tishun added the type: bug A general bug label Sep 13, 2024
@tishun tishun added this to the 6.5.0.RELEASE milestone Sep 13, 2024
@Roiocam Roiocam deleted the fix-deadlock branch September 26, 2024 08:05
tishun pushed a commit to tishun/lettuce-core that referenced this pull request Nov 1, 2024
@Roiocam @tishun
fix:deadlock when reentrant exclusive lock redis#2905 redis#2879 (red…
c49a178 
…is#2961)

* fix:deadlock when reentrant exclusive lock redis#2905

* confirm won't blocking other thread

* apply suggestions
@tishun tishun mentioned this pull request Nov 1, 2024
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tishun added a commit that referenced this pull request Nov 1, 2024
@tishun @Roiocam
fix:deadlock when reentrant exclusive lock #2905 #2879 (#2961) (#3041)
08096cf 
* fix:deadlock when reentrant exclusive lock #2905

* confirm won't blocking other thread

* apply suggestions

Co-authored-by: Andy(Jingzhang)Chen <[email protected]>
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Deadlock in SharedLock
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@Roiocam @tishun