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Date: Tue, 28 Feb 2012 19:37:46 +0000 (UTC)
From: "Todd Lipcon (Created) (JIRA)" <jira@apache.org>
To: hdfs-dev@hadoop.apache.org
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Subject: [jira] [Created] (HDFS-3025) Automatic log sync shouldn't happen
 inside logEdit path
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Automatic log sync shouldn't happen inside logEdit path
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                 Key: HDFS-3025
                 URL: https://issues.apache.org/jira/browse/HDFS-3025
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: name-node, performance
    Affects Versions: 0.23.3
            Reporter: Todd Lipcon
            Assignee: Todd Lipcon


HDFS-3020 fixes the "automatic log sync" functionality so that, when logEdits is called without log sync, it eventually triggers a sync. That sync ends up being inline, though, which means the FSN lock is usually held during it. This causes a bunch of threads to pile up.

Instead, we should have it just set a "syncNeeded" flag and trigger a sync from another thread which isn't holding the lock (or from the same thread using a "logSyncIfNeeded" call).

(credit to the FB branch for this idea)

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