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Date: Mon, 25 Mar 2013 18:17:18 +0000 (UTC)
From: "Amitanand Aiyer (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12608148.1348006918747.50127.1364235438150@arcas>
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References: <JIRA.12608148.1348006918747@arcas>
Subject: [jira] [Commented] (HBASE-6813) Optimise the time spent holding the
 updateLock under log roll
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    [ https://issues.apache.org/jira/browse/HBASE-6813?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13612935#comment-13612935 ] 

Amitanand Aiyer commented on HBASE-6813:
----------------------------------------

Overall, we have seen that the update lock used to be held for about 500-700ms before the diff. 

Will get some numbers on how much writing the first dummy entry contributes.
                
> Optimise the time spent holding the updateLock under log roll
> -------------------------------------------------------------
>
>                 Key: HBASE-6813
>                 URL: https://issues.apache.org/jira/browse/HBASE-6813
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Amitanand Aiyer
>            Assignee: Amitanand Aiyer
>            Priority: Minor
>             Fix For: 0.89-fb
>
>
> Log roll entails syncing the old log, closing it and creating a new log file.
> We currently do all the 3 steps while holding the updateLock. This causes latency spikes for puts during this time.
> We only need to sync the old log under the lock. Creating the new file, can be done before grabbing the lock. Closing the old file can be done after we release the lock.

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