[jira] Commented: (HADOOP-2330) Preallocate transaction log to improve namenode transaction logging performance

["Hairong Kuang (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-2330?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12623061#action_12623061 ] 

Hairong Kuang commented on HADOOP-2330:
---------------------------------------

Dhruba, this patch makes EditLogOutputStream to have two file handlers to the edit log: a random access file handler and a file output stream. I think we only need the file output stream handler. It would make the code more readable.
 

> Preallocate transaction log to improve namenode transaction logging performance
> -------------------------------------------------------------------------------
>
>                 Key: HADOOP-2330
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2330
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: dfs
>            Reporter: dhruba borthakur
>            Assignee: dhruba borthakur
>         Attachments: preallocateTransactionLog.patch, preallocateTransactionLog.patch, preallocateTransactionLog2.patch
>
>
> In the current implementation, the transaction log is opened in "append" mode and every new transaction is written to the end of the log. This means that new blocks get allocated to the edits file frequently.
> It is worth measuring the performance improvement when big chunks of the transaction log are allocated up front. Adding new transactions do not cause frequent block allocations for the edits log.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.