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From "Johan Oskarsson (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HADOOP-3232) Datanodes time out
Date Wed, 14 May 2008 11:21:55 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-3232?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Johan Oskarsson updated HADOOP-3232:
------------------------------------

    Attachment: du-nonblocking-v5-trunk.patch

1. Changed
2. Removed the reference to DU and call DU.this.run() instead.

Scheduling it with an Executor would still have a running thread that keeps track of the scheduling,
no? ScheduledThreadPoolExecutor for example.
The other example was starting a thread inside getUsed() then returning the old value while
the DU runs? Wouldn't that cause problems where getUsed is called very infrequently? Perhaps
this is never an issue?

Anyway, I added the comment about improving this with a non permanent thread anyway, in the
most common case I guess that would work fine.

As mentioned this patch will cause one new findbugs error, starting a thread in the constructor,
hard to avoid without having a new method to start it, breaking the public interface.

> Datanodes time out
> ------------------
>
>                 Key: HADOOP-3232
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3232
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: dfs
>    Affects Versions: 0.16.2, 0.16.3, 0.16.4
>         Environment: 10 node cluster + 1 namenode
>            Reporter: Johan Oskarsson
>            Priority: Critical
>             Fix For: 0.18.0
>
>         Attachments: du-nonblocking-v1.patch, du-nonblocking-v2-trunk.patch, du-nonblocking-v4-trunk.patch,
du-nonblocking-v5-trunk.patch, hadoop-hadoop-datanode-new.log, hadoop-hadoop-datanode-new.out,
hadoop-hadoop-datanode.out, hadoop-hadoop-namenode-master2.out
>
>
> I recently upgraded to 0.16.2 from 0.15.2 on our 10 node cluster.
> Unfortunately we're seeing datanode timeout issues. In previous versions we've often
seen in the nn webui that one or two datanodes "last contact" goes from the usual 0-3 sec
to ~200-300 before it drops down to 0 again.
> This causes mild discomfort but the big problems appear when all nodes do this at once,
as happened a few times after the upgrade.
> It was suggested that this could be due to namenode garbage collection, but looking at
the gc log output it doesn't seem to be the case.

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