[jira] [Created] (HBASE-10499) In write heavy scenario one of the regions does not get flushed causing RegionTooBusyException

["ramkrishna.s.vasudevan (JIRA)" <ji...@apache.org>]

ramkrishna.s.vasudevan created HBASE-10499:
----------------------------------------------

             Summary: 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
            Reporter: ramkrishna.s.vasudevan
            Assignee: ramkrishna.s.vasudevan
            Priority: Critical
             Fix For: 0.98.0, 0.98.1


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.



--
This message was sent by Atlassian JIRA
(v6.1.5#6160)