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Posted to hdfs-issues@hadoop.apache.org by "Tsz Wo (Nicholas), SZE (JIRA)" <ji...@apache.org> on 2011/07/26 22:44:09 UTC
[jira] [Created] (HDFS-2206) Add read-write lock to DatanodeManager
Add read-write lock to DatanodeManager
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Key: HDFS-2206
URL: https://issues.apache.org/jira/browse/HDFS-2206
Project: Hadoop HDFS
Issue Type: Sub-task
Reporter: Tsz Wo (Nicholas), SZE
Assignee: Tsz Wo (Nicholas), SZE
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[jira] [Commented] (HDFS-2206) Add read-write lock to
DatanodeManager
Posted by "Todd Lipcon (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/HDFS-2206?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13071354#comment-13071354 ]
Todd Lipcon commented on HDFS-2206:
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If we're adding more locks, can we take a step back and make sure it's well documented in the code what the lock heirarchy and granularity is?
I think this new refactoring work will help make it easier to understand this, but for operations which still cross the block-namespace chasm, it would be good to know which lock should be taken first, etc.
It would also be great if we could have a "debug mode" in which the locks assert their own heirarchy. For example, I've seen some systems assign an integer "level" to each lock, and use a threadlocal stack to keep track of the highest level lock taken. If you try to take a lower level lock while holding a higher level one, it will panic.
> Add read-write lock to DatanodeManager
> --------------------------------------
>
> Key: HDFS-2206
> URL: https://issues.apache.org/jira/browse/HDFS-2206
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: name-node
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
>
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