Le 16/11/12 01:56, Stack a écrit :
On Thu, Nov 15, 2012 at 5:21 AM, Guillaume Perrot <[email protected]> wrote:
It happens when several tables are being compacted and/or when there is
several scanners running.
It happens for a particular region? Anything you can tell about the
server looking in your cluster monitoring? Is it running hot? What
do the hbase regionserver stats in UI say? Anything interesting about
compaction queues or requests?
Hi, thanks for your answser Stack. I will take the lead on that
thread from now on.
It does not happens on any particular region. Actually, things get
better now since compactions have been performed on all tables and
have been stopped.
Nevertheless, we face a dramatic decrease of performances
(especially on random gets) of the overall cluster:
Despite the fact we double our number of region servers (from 8 to
16) and despite the fact that these region server CPU load are just
about 10% to 30%, performances are really bad : very often an light
increase of request lead to a clients locked on request, very long
response time. It looks like a contention / deadlock somewhere in
the HBase client and C code.
If you look at the thread dump all handlers are occupied serving
requests? These timedout requests couldn't get into the server?
We will investigate on that and report to you.
Before the timeouts, we observe an increasing CPU load on a single region
server and if we add region servers and wait for rebalancing, we always
have the same region server causing problems like these:
2012-11-14 20:47:08,443 WARN org.apache.hadoop.ipc.HBaseServer: IPC
Server Responder, call
multi(org.apache.hadoop.hbase.client.MultiAction@2c3da1aa), rpc
version=1, client version=29, methodsFingerPrint=54742778 from
<ip>:45334: output error
2012-11-14 20:47:08,443 WARN org.apache.hadoop.ipc.HBaseServer: IPC
Server handler 3 on 60020 caught: java.nio.channels.ClosedChannelException
at sun.nio.ch.SocketChannelImpl.ensureWriteOpen(SocketChannelImpl.java:133)
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:324)
at
org.apache.hadoop.hbase.ipc.HBaseServer.channelWrite(HBaseServer.java:1653)
at
org.apache.hadoop.hbase.ipc.HBaseServer$Responder.
processResponse(HBaseServer.java:924)
at
org.apache.hadoop.hbase.ipc.HBaseServer$Responder.
doRespond(HBaseServer.java:1003)
at
org.apache.hadoop.hbase.ipc.HBaseServer$Call.sendResponseIfReady(
HBaseServer.java:409)
at
org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:1346)
With the same access patterns, we did not have this issue in HBase 0.90.3.
The above is other side of the timeout -- the client is gone.
Can you explain the rising CPU?
No there is no explanation (no high access a a given region for
exemple). But this specific problem has gone when we finished
compactions.
Is it iowait on this box because of
compactions? Bad disk? Always same regionserver or issue moves
around?
Sorry for all the questions. 0.92 should be better than 0.90
Our experience is currently the exact opposite : for us, 0.92 seems
to be times slower than the 0.90.3.
generally (0.94 even better still -- can you go there?).
We can go to 0.94 but unfortunately, we CANNOT GO BACK (the same way
we cannot go back to 0.90.3, since there is apparently a
modification of the format of the ROOT table).
The upgrade works, but the downgrade not. And we are afraid of
having even more "new" problems with 0.94 and be forced to rollback
to 0.90.3 (with some days of data loses).
Thanks for your reply we will continue to investigate.
Interesting
that these issues show up post upgrade. I can't think of a reason why
the different versions would bring this on...
St.Ack
