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https://issues.apache.org/jira/browse/HBASE-2312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13138908#comment-13138908
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Phabricator commented on HBASE-2312:
------------------------------------
khemani has commented on the revision "HBASE-2312 [jira] Possible data loss
when RS goes into GC pause while rolling HLog".
INLINE COMMENTS
src/main/java/org/apache/hadoop/hbase/master/MasterFileSystem.java:223
Basically what Nicolas said ... setting the abort flag here will not have any
immediate effect.
From HMaster code
status.setStatus("Splitting logs after master startup");
this.fileSystemManager.
splitLogAfterStartup(this.serverManager.getOnlineServers().keySet());
// Make sure root and meta assigned before proceeding.
assignRootAndMeta(status);
the master thread will try to assignRootAndMeta() even if
splitLogAfterStartup() returns with abort flag set. May be if HMaster.abort()
had set the interrupt flag on at least the main master thread then it might
have worked ...
REVISION DETAIL
https://reviews.facebook.net/D99
> Possible data loss when RS goes into GC pause while rolling HLog
> ----------------------------------------------------------------
>
> Key: HBASE-2312
> URL: https://issues.apache.org/jira/browse/HBASE-2312
> Project: HBase
> Issue Type: Bug
> Components: master, regionserver
> Affects Versions: 0.90.0
> Reporter: Karthik Ranganathan
> Assignee: Nicolas Spiegelberg
> Priority: Critical
> Fix For: 0.92.0
>
> Attachments: D99.1.patch
>
>
> There is a very corner case when bad things could happen(ie data loss):
> 1) RS #1 is going to roll its HLog - not yet created the new one, old one
> will get no more writes
> 2) RS #1 enters GC Pause of Death
> 3) Master lists HLog files of RS#1 that is has to split as RS#1 is dead,
> starts splitting
> 4) RS #1 wakes up, created the new HLog (previous one was rolled) and
> appends an edit - which is lost
> The following seems like a possible solution:
> 1) Master detects RS#1 is dead
> 2) The master renames the /hbase/.logs/<regionserver name> directory to
> something else (say /hbase/.logs/<regionserver name>-dead)
> 3) Add mkdir support (as opposed to mkdirs) to HDFS - so that a file
> create fails if the directory doesn't exist. Dhruba tells me this is very
> doable.
> 4) RS#1 comes back up and is not able create the new hlog. It restarts
> itself.
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