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https://issues.apache.org/jira/browse/HBASE-10499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13902948#comment-13902948
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ramkrishna.s.vasudevan commented on HBASE-10499:
------------------------------------------------
bq.Can you enable "hbase.regionserver.servlet.show.queuedump" so that you can
get dump of flushQueue ?
This cluster is stopped now. So next time when i run i can enable this.
[~fenghh]
Thanks for the analysis. I was actually analysing another part of the code to
see if there is any chance where the flushQueue is not able to pick up the
region as you said and mainly due to the equals and compareTo method in
FlushRegionEntry. But could not find any proper evidence. What I was
thiniking was from time 2014-02-11 08:44:32,433 to 2014-02-11 08:44:34,033
there were lot of flush requests, so may be some problem with the way the
region was picked up based on the time based comparsion in the queue. But
later felt that because every time there was a flush request.
The HRegion.shouldFlush() does not check for the size instead only checks for
the time of the oldest edit. Also the HLog rollWriter() also checks if there
was an oldest edit. So this is what made me think may be the flush size is
calculated wrong.
I will try to get the master logs. The cluster is stopped now but i think the
logs should be available.
> In write heavy scenario one of the regions does not get flushed causing
> RegionTooBusyException
> ----------------------------------------------------------------------------------------------
>
> Key: HBASE-10499
> URL: https://issues.apache.org/jira/browse/HBASE-10499
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.98.0
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Priority: Critical
> Fix For: 0.98.1, 0.99.0
>
> Attachments: HBASE-10499.patch,
> hbase-root-regionserver-ip-10-93-128-92.zip, t1.dump, t2.dump,
> workloada_0.98.dat
>
>
> I got this while testing 0.98RC. But am not sure if it is specific to this
> version. Doesn't seem so to me.
> Also it is something similar to HBASE-5312 and HBASE-5568.
> Using 10 threads i do writes to 4 RS using YCSB. The table created has 200
> regions. In one of the run with 0.98 server and 0.98 client I faced this
> problem like the hlogs became more and the system requested flushes for those
> many regions.
> One by one everything was flushed except one and that one thing remained
> unflushed. The ripple effect of this on the client side
> {code}
> com.yahoo.ycsb.DBException:
> org.apache.hadoop.hbase.client.RetriesExhaustedWithDetailsException: Failed
> 54 actions: RegionTooBusyException: 54 times,
> at com.yahoo.ycsb.db.HBaseClient.cleanup(HBaseClient.java:245)
> at com.yahoo.ycsb.DBWrapper.cleanup(DBWrapper.java:73)
> at com.yahoo.ycsb.ClientThread.run(Client.java:307)
> Caused by:
> org.apache.hadoop.hbase.client.RetriesExhaustedWithDetailsException: Failed
> 54 actions: RegionTooBusyException: 54 times,
> at
> org.apache.hadoop.hbase.client.AsyncProcess$BatchErrors.makeException(AsyncProcess.java:187)
> at
> org.apache.hadoop.hbase.client.AsyncProcess$BatchErrors.access$500(AsyncProcess.java:171)
> at
> org.apache.hadoop.hbase.client.AsyncProcess.getErrors(AsyncProcess.java:897)
> at
> org.apache.hadoop.hbase.client.HTable.backgroundFlushCommits(HTable.java:961)
> at
> org.apache.hadoop.hbase.client.HTable.flushCommits(HTable.java:1225)
> at com.yahoo.ycsb.db.HBaseClient.cleanup(HBaseClient.java:232)
> ... 2 more
> {code}
> On one of the RS
> {code}
> 2014-02-11 08:45:58,714 INFO [regionserver60020.logRoller] wal.FSHLog: Too
> many hlogs: logs=38, maxlogs=32; forcing flush of 23 regions(s):
> 97d8ae2f78910cc5ded5fbb1ddad8492, d396b8a1da05c871edcb68a15608fdf2,
> 01a68742a1be3a9705d574ad68fec1d7, 1250381046301e7465b6cf398759378e,
> 127c133f47d0419bd5ab66675aff76d4, 9f01c5d25ddc6675f750968873721253,
> 29c055b5690839c2fa357cd8e871741e, ca4e33e3eb0d5f8314ff9a870fc43463,
> acfc6ae756e193b58d956cb71ccf0aa3, 187ea304069bc2a3c825bc10a59c7e84,
> 0ea411edc32d5c924d04bf126fa52d1e, e2f9331fc7208b1b230a24045f3c869e,
> d9309ca864055eddf766a330352efc7a, 1a71bdf457288d449050141b5ff00c69,
> 0ba9089db28e977f86a27f90bbab9717, fdbb3242d3b673bbe4790a47bc30576f,
> bbadaa1f0e62d8a8650080b824187850, b1a5de30d8603bd5d9022e09c574501b,
> cc6a9fabe44347ed65e7c325faa72030, 313b17dbff2497f5041b57fe13fa651e,
> 6b788c498503ddd3e1433a4cd3fb4e39, 3d71274fe4f815882e9626e1cfa050d1,
> acc43e4b42c1a041078774f4f20a3ff5
> ......................................................
> 2014-02-11 08:47:49,580 INFO [regionserver60020.logRoller] wal.FSHLog: Too
> many hlogs: logs=53, maxlogs=32; forcing flush of 2 regions(s):
> fdbb3242d3b673bbe4790a47bc30576f, 6b788c498503ddd3e1433a4cd3fb4e39
> {code}
> {code}
> 2014-02-11 09:42:44,237 INFO [regionserver60020.periodicFlusher]
> regionserver.HRegionServer: regionserver60020.periodicFlusher requesting
> flush for region
> usertable,user3654,1392107806977.fdbb3242d3b673bbe4790a47bc30576f. after a
> delay of 16689
> 2014-02-11 09:42:44,237 INFO [regionserver60020.periodicFlusher]
> regionserver.HRegionServer: regionserver60020.periodicFlusher requesting
> flush for region
> usertable,user6264,1392107806983.6b788c498503ddd3e1433a4cd3fb4e39. after a
> delay of 15868
> 2014-02-11 09:42:54,238 INFO [regionserver60020.periodicFlusher]
> regionserver.HRegionServer: regionserver60020.periodicFlusher requesting
> flush for region
> usertable,user3654,1392107806977.fdbb3242d3b673bbe4790a47bc30576f. after a
> delay of 20847
> 2014-02-11 09:42:54,238 INFO [regionserver60020.periodicFlusher]
> regionserver.HRegionServer: regionserver60020.periodicFlusher requesting
> flush for region
> usertable,user6264,1392107806983.6b788c498503ddd3e1433a4cd3fb4e39. after a
> delay of 20099
> 2014-02-11 09:43:04,238 INFO [regionserver60020.periodicFlusher]
> regionserver.HRegionServer: regionserver60020.periodicFlusher requesting
> flush for region
> usertable,user3654,1392107806977.fdbb3242d3b673bbe4790a47bc30576f. after a
> delay of 8677
> {code}
> {code}
> 2014-02-11 10:31:21,020 INFO [regionserver60020.logRoller] wal.FSHLog: Too
> many hlogs: logs=54, maxlogs=32; forcing flush of 1 regions(s):
> fdbb3242d3b673bbe4790a47bc30576f
> {code}
> I restarted another RS and there were region movements with other regions but
> this region stays with the RS that has this issue. One important observation
> is that in HRegion.internalflushCache() we need to add a debug log here
> {code}
> // If nothing to flush, return and avoid logging start/stop flush.
> if (this.memstoreSize.get() <= 0) {
> return false;
> }
> {code}
> Because we can see that the region is requsted for a flush but it does not
> happen and no logs related to flush are printed in the logs. so due to some
> reason this memstore.size() has become 0( I assume this). The earlier bugs
> were also due to similar reason.
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