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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-1989) When checkpointing by backup node occurs parallely when a file is being closed by a client then Exception occurs saying no journal streams.
Date Wed, 15 Jun 2011 10:48:47 GMT

    [ https://issues.apache.org/jira/browse/HDFS-1989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13049710#comment-13049710
] 

ramkrishna.s.vasudevan commented on HDFS-1989:
----------------------------------------------

Hi Todd,
In the backup name node side during checkpointing 
{noformat}
    bnImage.loadCheckpoint(sig);
    sig.validateStorageInfo(bnImage);
    bnImage.saveCheckpoint();
{noformat}

{noformat}
void saveCheckpoint() throws IOException {
    saveNamespace(false);
  }
{noformat}

In savenamespace
{noformat}
  void saveNamespace(boolean renewCheckpointTime) throws IOException {
 
    // try to restore all failed edit logs here
    assert editLog != null : "editLog must be initialized";
    storage.attemptRestoreRemovedStorage();

    editLog.close();
{noformat}


So here the editlogs are getting closed in the Checkpoint flow.

This is where the problem comes when the client tries to issue a close file after editLog.close()
is exceuted.



> When checkpointing by backup node occurs parallely when a file is being closed by a client
then Exception occurs saying no journal streams. 
> --------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-1989
>                 URL: https://issues.apache.org/jira/browse/HDFS-1989
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: name-node
>    Affects Versions: 0.23.0
>            Reporter: ramkrishna.s.vasudevan
>             Fix For: 0.23.0
>
>
> Backup namenode initiates the checkpointing process. 
> As a part of checkpointing based on the timestamp it tries to download the FSImage or
use the existing one.
> Then it tries to save the FSImage.
> During this time it tries to close the editLog streams.
> Parallely when a client tries to close a file just after the checkpointing process closes
the editLog Stream then we get an exception saying
> java.io.IOException: java.lang.IllegalStateException: !!! WARNING !!! File system changes
are not persistent. No journal streams.
> Here the saveNameSpace api closes all the editlog streams resulting in this issue.
>  

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