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https://issues.apache.org/jira/browse/HBASE-10499?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13902978#comment-13902978
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Feng Honghua commented on HBASE-10499:
--------------------------------------
bq.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
If my understanding is correct, these are by design. These two are both to
flush regions with old enough edits even their memstoreSize is below flush
threshold(to reduce the number of log files at the cost of hfiles with small
sizes), so it's natural they don't check whether memstoreSize > someValue(they
assume and tolerate memstoreSize with small size). And a region will be
selected to flush by rollWriter/periodicalFlusher only when they (do) have some
'old' edits, so the region's memstoreSize *must not* <= 0(this is an implicit
invariant and can be asserted, but not be check-and-exit)
> 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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