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https://issues.apache.org/jira/browse/HBASE-23181?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16960662#comment-16960662
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Michael Stack commented on HBASE-23181:
---------------------------------------
Ran cluster test with heavy load overrunning hbase against branch-2.2 (i.e. w/
this patch). This problem did not show (Plenty of others did but that is
another story). Will run more but looking good.
> Blocked WAL archive: "LogRoller: Failed to schedule flush of XXXX, because it
> is not online on us"
> --------------------------------------------------------------------------------------------------
>
> Key: HBASE-23181
> URL: https://issues.apache.org/jira/browse/HBASE-23181
> Project: HBase
> Issue Type: Bug
> Components: regionserver, wal
> Affects Versions: 2.2.1
> Reporter: Michael Stack
> Assignee: Duo Zhang
> Priority: Major
> Fix For: 3.0.0, 2.3.0, 2.1.8, 2.2.3
>
>
> On a heavily loaded cluster, WAL count keeps rising and we can get into a
> state where we are not rolling the logs off fast enough. In particular, there
> is this interesting state at the extreme where we pick a region to flush
> because 'Too many WALs' but the region is actually not online. As the WAL
> count rises, we keep picking a region-to-flush that is no longer on the
> server. This condition blocks our being able to clear WALs; eventually WALs
> climb into the hundreds and the RS goes zombie with a full Call queue that
> starts throwing CallQueueTooLargeExceptions (bad if this servers is the one
> carrying hbase:meta): i.e. clients fail to access the RegionServer.
> One symptom is a fast spike in WAL count for the RS. A restart of the RS will
> break the bind.
> Here is how it looks in the log:
> {code}
> # Here is region closing....
> 2019-10-16 23:10:55,897 INFO
> org.apache.hadoop.hbase.regionserver.handler.UnassignRegionHandler: Closed
> 8ee433ad59526778c53cc85ed3762d0b
> ....
> # Then soon after ...
> 2019-10-16 23:11:44,041 WARN org.apache.hadoop.hbase.regionserver.LogRoller:
> Failed to schedule flush of 8ee433ad59526778c53cc85ed3762d0b, because it is
> not online on us
> 2019-10-16 23:11:45,006 INFO
> org.apache.hadoop.hbase.regionserver.wal.AbstractFSWAL: Too many WALs;
> count=45, max=32; forcing flush of 1 regions(s):
> 8ee433ad59526778c53cc85ed3762d0b
> ...
> # Later...
> 2019-10-16 23:20:25,427 INFO
> org.apache.hadoop.hbase.regionserver.wal.AbstractFSWAL: Too many WALs;
> count=542, max=32; forcing flush of 1 regions(s):
> 8ee433ad59526778c53cc85ed3762d0b
> 2019-10-16 23:20:25,427 WARN org.apache.hadoop.hbase.regionserver.LogRoller:
> Failed to schedule flush of 8ee433ad59526778c53cc85ed3762d0b, because it is
> not online on us
> {code}
> I've seen this runaway WALs 2.2.1. I've seen runaway WALs in a 1.2.x version
> regularly that had HBASE-16721 fix in it, but can't say yet if it was for
> same reason as above.
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