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Posted to common-dev@hadoop.apache.org by "Igor Bolotin (JIRA)" <ji...@apache.org> on 2006/04/15 05:40:00 UTC
[jira] Created: (HADOOP-139) Deadlock in LocalFileSystem
lock/release
Deadlock in LocalFileSystem lock/release
-----------------------------------------
Key: HADOOP-139
URL: http://issues.apache.org/jira/browse/HADOOP-139
Project: Hadoop
Type: Bug
Components: fs
Reporter: Igor Bolotin
LocalFileSystem lock/release methods marked synchronized and inside they lock file channel - this produces deadlock situation. Let's see how it happens:
1. First thread locks the file and starts some long-running process.
2. Second thread tries to lock the file and it blocks inside channel lock method. It keeps LocalFileSystem instance "locked" as well.
3. First thread finished it's processing and tries to release lock - it blocks because LocalFileSystem instance is "locked" by second thread - both threads are waiting to each other.
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[jira] Updated: (HADOOP-139) Deadlock in LocalFileSystem
lock/release
Posted by "Igor Bolotin (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/HADOOP-139?page=all ]
Igor Bolotin updated HADOOP-139:
--------------------------------
Attachment: deadlock.patch
Attached is proposed patch. I removed entire lock/release method synchronization and replaced it with critical section synchronization for sets accesses - leaving channel lock/release calls outside of synchronized statement.
> Deadlock in LocalFileSystem lock/release
> ----------------------------------------
>
> Key: HADOOP-139
> URL: http://issues.apache.org/jira/browse/HADOOP-139
> Project: Hadoop
> Type: Bug
> Components: fs
> Reporter: Igor Bolotin
> Attachments: deadlock.patch
>
> LocalFileSystem lock/release methods marked synchronized and inside they lock file channel - this produces deadlock situation. Let's see how it happens:
> 1. First thread locks the file and starts some long-running process.
> 2. Second thread tries to lock the file and it blocks inside channel lock method. It keeps LocalFileSystem instance "locked" as well.
> 3. First thread finished it's processing and tries to release lock - it blocks because LocalFileSystem instance is "locked" by second thread - both threads are waiting to each other.
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[jira] Commented: (HADOOP-139) Deadlock in LocalFileSystem
lock/release
Posted by "Doug Cutting (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/HADOOP-139?page=comments#action_12374983 ]
Doug Cutting commented on HADOOP-139:
-------------------------------------
I just committed this. Thanks, Igor!
The patch did not apply directly, due to other changes made to Hadoop since you contributed it. So I had to apply parts of it manually. Please check that it still looks correct. Thanks!
> Deadlock in LocalFileSystem lock/release
> ----------------------------------------
>
> Key: HADOOP-139
> URL: http://issues.apache.org/jira/browse/HADOOP-139
> Project: Hadoop
> Type: Bug
> Components: fs
> Reporter: Igor Bolotin
> Attachments: deadlock.patch
>
> LocalFileSystem lock/release methods marked synchronized and inside they lock file channel - this produces deadlock situation. Let's see how it happens:
> 1. First thread locks the file and starts some long-running process.
> 2. Second thread tries to lock the file and it blocks inside channel lock method. It keeps LocalFileSystem instance "locked" as well.
> 3. First thread finished it's processing and tries to release lock - it blocks because LocalFileSystem instance is "locked" by second thread - both threads are waiting to each other.
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[jira] Resolved: (HADOOP-139) Deadlock in LocalFileSystem
lock/release
Posted by "Doug Cutting (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/HADOOP-139?page=all ]
Doug Cutting resolved HADOOP-139:
---------------------------------
Fix Version: 0.2
Resolution: Fixed
Assign To: Doug Cutting
> Deadlock in LocalFileSystem lock/release
> ----------------------------------------
>
> Key: HADOOP-139
> URL: http://issues.apache.org/jira/browse/HADOOP-139
> Project: Hadoop
> Type: Bug
> Components: fs
> Reporter: Igor Bolotin
> Assignee: Doug Cutting
> Fix For: 0.2
> Attachments: deadlock.patch
>
> LocalFileSystem lock/release methods marked synchronized and inside they lock file channel - this produces deadlock situation. Let's see how it happens:
> 1. First thread locks the file and starts some long-running process.
> 2. Second thread tries to lock the file and it blocks inside channel lock method. It keeps LocalFileSystem instance "locked" as well.
> 3. First thread finished it's processing and tries to release lock - it blocks because LocalFileSystem instance is "locked" by second thread - both threads are waiting to each other.
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