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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-2191) Move datanodeMap from FSNamesystem to DatanodeManager
Date Tue, 26 Jul 2011 20:48:09 GMT

    [ https://issues.apache.org/jira/browse/HDFS-2191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13071349#comment-13071349

Tsz Wo (Nicholas), SZE commented on HDFS-2191:

heartbeatIntervalSeconds is actually in milliseconds. So can you call it heartbeatIntervalMilliSeconds.
Rest of the code looks correct.

heartbeatIntervalSeconds uses DFSConfigKeys.DFS_HEARTBEAT_INTERVAL_KEY and the default is
3 (seconds).

DatanodeManager#getDatanode() - how is the map access synchronized in this?
> It should accquire the write lock of DatanodeManager when we have read-write lock in
DatanodeManager in the future.
We should track this with a jira, since the synchronization that is in the current code is
not correct.

I went through the patch.  It did not change any existing synchronization on datanodesMap.
 However, the access of DatanodeManager#getDatanode(..) is sometimes not synchronized.  You
are right that the current synchronization is incorrect.

I have created HDFS-2206 for adding read-write lock to DatanodeManager.

> Move datanodeMap from FSNamesystem to DatanodeManager
> -----------------------------------------------------
>                 Key: HDFS-2191
>                 URL: https://issues.apache.org/jira/browse/HDFS-2191
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: name-node
>            Reporter: Tsz Wo (Nicholas), SZE
>            Assignee: Tsz Wo (Nicholas), SZE
>         Attachments: h2191_20110723.patch, h2191_20110723b.patch, h2191_20110726.patch

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