[jira] [Commented] (NIFI-5331) SequentialAccessWriteAheadLog: poisioned journal requires restart

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/NIFI-5331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16581137#comment-16581137 ] 

ASF GitHub Bot commented on NIFI-5331:
--------------------------------------

GitHub user markap14 opened a pull request:

    https://github.com/apache/nifi/pull/2952

    NIFI-5331: When checkpointing SequentialAccessWriteAheadLog, if the j…

    …ournal is not healthy, ensure that we roll it over and ensure that if an Exception is thrown when attempting to fsync() or close() the journal, we continue creating a new one.
    
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You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/markap14/nifi NIFI-5331

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/nifi/pull/2952.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #2952
    
----
commit 4cb346703ba05b8c3180bd0dfe9e113dedcdbc56
Author: Mark Payne <ma...@...>
Date:   2018-08-15T14:23:49Z

    NIFI-5331: When checkpointing SequentialAccessWriteAheadLog, if the journal is not healthy, ensure that we roll it over and ensure that if an Exception is thrown when attempting to fsync() or close() the journal, we continue creating a new one.

----


> SequentialAccessWriteAheadLog: poisioned journal requires restart
> -----------------------------------------------------------------
>
>                 Key: NIFI-5331
>                 URL: https://issues.apache.org/jira/browse/NIFI-5331
>             Project: Apache NiFi
>          Issue Type: Bug
>          Components: Core Framework
>    Affects Versions: 1.6.0
>            Reporter: Brandon DeVries
>            Assignee: Mark Payne
>            Priority: Major
>             Fix For: 1.8.0
>
>
> If using the SequentialAccessWriteAheadLog, once a journal becomes poisoned, NiFi can't recover without a restart.  
> SequentialAccessWriteAheadLog uses a LengthDelimitedJournal which has a "poisoned" flag[1].  This is initially set "false", but is set true if an Exceptions or Throwable is encountered on a write operation[2].  Once poisoned, calls to update()[3] will result in a call to checkState()[4] which then throws an IOException stating, "Cannot update journal file... If the repository is able to checkpoint, then this problem will resolve itself..."  SequentialAccessWriteAheadLog.checkpoint()[5] creates a new LengthDelimitedJournal which would hypothetically have a cleared "poisoned" flag .  However, before creating that new Journal, it calls journal.fsync()[6], which calls checkState(), which throws the above IOException if poisoned == true.  So, the FlowFileRepository enters a state where it cannot be written to, and cannot recover, until the instance is restarted.
>  
> [1] [https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-commons/nifi-write-ahead-log/src/main/java/org/apache/nifi/wali/LengthDelimitedJournal.java#L70] 
> [2] [https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-commons/nifi-write-ahead-log/src/main/java/org/apache/nifi/wali/LengthDelimitedJournal.java#L208] 
> [3] [https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-commons/nifi-write-ahead-log/src/main/java/org/apache/nifi/wali/LengthDelimitedJournal.java#L178]
> [4] [https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-commons/nifi-write-ahead-log/src/main/java/org/apache/nifi/wali/LengthDelimitedJournal.java#L217] 
> [5] [https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-commons/nifi-write-ahead-log/src/main/java/org/apache/nifi/wali/SequentialAccessWriteAheadLog.java#L279] 
> [6] [https://github.com/apache/nifi/blob/rel/nifi-1.6.0/nifi-commons/nifi-write-ahead-log/src/main/java/org/apache/nifi/wali/SequentialAccessWriteAheadLog.java#L259] 



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