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https://issues.apache.org/jira/browse/HBASE-23181?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16956374#comment-16956374
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Michael Stack commented on HBASE-23181:
---------------------------------------
Studying a live 1.2.x deploy (trying to dig up clues on why we go bad), the
flush went bad on a region split; thereafter we could no longer flush the
parent yet we kept trying to so we could clear the oldest WAL.
2019-10-18 20:15:03,343 INFO org.apache.hadoop.hbase.regionserver.SplitRequest:
Region split, hbase:meta updated, and report to master.
Parent=XYZ,7dd2c3e4-a908-42cd-9dd7-bf20651acdbb,1522152449885.0f4cd0e561a660ea6b11d4703258cd60.,
new regions:
XYZ,7dd2c3e4-a908-42cd-9dd7-bf20651acdbb,1571429702384.b912e2a50897e5ca002107dd472efcfe.,
XYZ,7dd6df6c-1949-4116-a5ed-008f6d4ae35a,1571429702384.0890b696df81a28a1ba4e9e00e8c43c0..
Split took 0sec
Then later...
2019-10-18 20:19:33,622 INFO org.apache.hadoop.hbase.regionserver.wal.FSHLog:
Too many WALs; count=33, max=32; forcing flush of 8 regions(s):
4ab5672c35baa260ce3742e403c03d3b, 0890b696df81a28a1ba4e9e00e8c43c0,
89ca70c06e66c0fe8732d7ebfc9e6eff, f7b98bf63c74325a7ee703be48cbd991,
0cba425e6b3caec2af1ff0d52eaffd92, 0f4cd0e561a660ea6b11d4703258cd60,
9758363e8d237b8559385b4f2a2da78d, b912e2a50897e5ca002107dd472efcfe
but...
2019-10-18 20:19:33,623 WARN org.apache.hadoop.hbase.regionserver.LogRoller:
Failed to schedule flush of 0f4cd0e561a660ea6b11d4703258cd60, region=null,
requester=null
And so on.
So, seems like split can be problem in branch-1; i.e. we may not clear the
region from the sequenceidaccounting on split.
> 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
> Affects Versions: 2.2.1
> Reporter: Michael Stack
> Priority: Major
>
> 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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