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Posted to issues@bookkeeper.apache.org by GitBox <gi...@apache.org> on 2021/01/18 09:09:26 UTC
[GitHub] [bookkeeper] Shoothzj opened a new issue #2544: ConcurrentModificationException when print LinkedList
Shoothzj opened a new issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544
**BUG REPORT**
***Describe the bug***
***To Reproduce***
### What should we do ?
Do not print the linkedList
or
use read write lock to protect the list
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[GitHub] [bookkeeper] Shoothzj commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762298777
> that variable should be a CopyOnWriteArrayList and not a simple LinkedList
>
> see here:
> https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForEntryLogPerLedger.java#L277
>
> probably this issue is a result of a refactor
>
> otherwise we should take care of synchronization in all of the accesses to the variable.
> given the hierarchy of classes I suggest to change the type to CopyOnWriteArrayList here
> https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForSingleEntryLog.java#L53
Apparently, change it to CopyOnWriteArrayList can fix this problem.
But may be there is another solution, see these code:
May be we should add synchronize on method **commitEntryMemTableFlush** and **prepareSortedLedgerStorageCheckpoint** in class EntryLogManagerForSingleEntryLog.
These code are committed in year 2018. I don't think it's a refactor probleam
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[GitHub] [bookkeeper] eolivelli edited a comment on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
eolivelli edited a comment on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762256303
that variable should be a CopyOnWriteArrayList and not a simple LinkedList
see here:
https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForEntryLogPerLedger.java#L277
probably this issue is a result of a refactor
otherwise we should take care of synchronization in all of the accesses to the variable.
given the hierarchy of classes I suggest to change the type to CopyOnWriteArrayList
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[GitHub] [bookkeeper] eolivelli commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
eolivelli commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762303349
probably add those new synchronization points may cause additional issues
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[GitHub] [bookkeeper] Shoothzj edited a comment on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj edited a comment on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762188925
> LinkedList is not thread safe. Any Bookie error log or some other information? @Shoothzj
Currently I have not log related to it, it has been rotated. Maybe concurrently open the ledger and flush?
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[GitHub] [bookkeeper] Shoothzj edited a comment on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj edited a comment on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762298777
> that variable should be a CopyOnWriteArrayList and not a simple LinkedList
>
> see here:
> https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForEntryLogPerLedger.java#L277
>
> probably this issue is a result of a refactor
>
> otherwise we should take care of synchronization in all of the accesses to the variable.
> given the hierarchy of classes I suggest to change the type to CopyOnWriteArrayList here
> https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForSingleEntryLog.java#L53
Apparently, change it to CopyOnWriteArrayList can fix this problem.
But may be there is another solution, see these code:
May be we should add synchronize on method **commitEntryMemTableFlush** and **prepareSortedLedgerStorageCheckpoint** in class **EntryLogManagerForSingleEntryLog**.
These code are committed in year 2018. I don't think it's a refactor probleam
----------------------------------------------------------------
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[GitHub] [bookkeeper] Shoothzj commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762314932
> probably add those new synchronization points may cause additional issues
The two children class of EntryLogManagerBase use different trick of sync.
One **EntryLogManagerForEntryLogPerLedger** use CopyOnWriteArrayList,
Another class EntryLogManagerForSingleEntryLog use volatile for replace reference, and synchronize for add
If we change **EntryLogManagerForSingleEntryLog** to CopyOnWriteArrayList, the other synchronize block like
seems useless, can be replace as
```java
rotatedLogChannels.clear();
```
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[GitHub] [bookkeeper] eolivelli commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
eolivelli commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762256303
that variable should be a CopyOnWriteArrayList and not a simple LinkedList
see here:
https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForEntryLogPerLedger.java#L277
probably this issue is a result of a refactor
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[GitHub] [bookkeeper] Shoothzj removed a comment on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj removed a comment on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762533327
> probably add those new synchronization points may cause additional issues
This annotation may prove that add sync is right, how about put sync on this method
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[GitHub] [bookkeeper] eolivelli edited a comment on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
eolivelli edited a comment on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762256303
that variable should be a CopyOnWriteArrayList and not a simple LinkedList
see here:
https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForEntryLogPerLedger.java#L277
probably this issue is a result of a refactor
otherwise we should take care of synchronization in all of the accesses to the variable.
given the hierarchy of classes I suggest to change the type to CopyOnWriteArrayList here
https://github.com/apache/bookkeeper/blob/master/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/EntryLogManagerForSingleEntryLog.java#L53
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[GitHub] [bookkeeper] WJL3333 commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
WJL3333 commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762136148
LinkedList is not thread safe. Any Bookie error log or some other information? @Shoothzj
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[GitHub] [bookkeeper] Shoothzj commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762188925
> LinkedList is not thread safe. Any Bookie error log or some other information? @Shoothzj
Currently I have not log according to it. Maybe concurrently open the ledger and flush?
----------------------------------------------------------------
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[GitHub] [bookkeeper] Shoothzj commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762533327
> probably add those new synchronization points may cause additional issues
This annotation may prove that add sync is right, how about put sync on this method
----------------------------------------------------------------
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[GitHub] [bookkeeper] Shoothzj commented on issue #2544: ConcurrentModificationException when print LinkedList
Posted by GitBox <gi...@apache.org>.
Shoothzj commented on issue #2544:
URL: https://github.com/apache/bookkeeper/issues/2544#issuecomment-762535378
> probably add those new synchronization points may cause additional issues
Refer to the addEntry method,
**EntryLogManagerForEntryLogPerLedger** locks per ledger
**EntryLogManagerForSingleEntryLog** locks itself
How about make the synchronization points only on call of **createNewLog** in class EntryLogManagerForSingleEntryLog.
Why **createNewLog** can't treat equality?
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