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From Nanheng Wu <nanhen...@gmail.com>
Subject Re: What's the region server doing?
Date Wed, 02 Mar 2011 01:30:40 GMT
You said "next", I don't know if this related at all but from the
master's thread dump, it says the disable is blocked by this thread
below, and it calling next:

Thread 27 (RegionManager.metaScanner):
  State: WAITING
  Blocked count: 69503
  Waited count: 68805
  Waiting on org.apache.hadoop.hbase.ipc.HBaseClient$Call@42fcac6
    java.lang.Object.wait(Native Method)
    $Proxy1.next(Unknown Source)

On Tue, Mar 1, 2011 at 5:22 PM, Nanheng Wu <nanhengwu@gmail.com> wrote:
> Thanks man I'll try that and post back when I find something. BTW, I
> ran the script to set the memstore flush size on .META., now I am
> seeing a lot less writing to HDFS from the .META RS and less
> compaction, unfortunately it's still low. :(
> On Tue, Mar 1, 2011 at 5:15 PM, Jean-Daniel Cryans <jdcryans@apache.org> wrote:
>> In that specific jstack it's doing nothing at all, but keep in mind
>> that it's only a snapshot of a precise moment in time. Try jstack'ing
>> a few times and at some point you should see the threads named like
>> "IPC Server handler xx on 60020" (where xx is a number) showing bigger
>> stack traces with HRegionServer doing stuff like get, next, put, etc
>> You should also try scanning '.META.' from the shell and if it's slow,
>> do the jstack'ing at the same time.
>> J-D
>> On Tue, Mar 1, 2011 at 5:07 PM, Nanheng Wu <nanhengwu@gmail.com> wrote:
>>> My cluster (10 nodes, hbase-0.20.6 + hadoop 0.20.2) is very very slow
>>> for any operation like disable table or delete. Master's thread dump
>>> says they are blocked by the metaScanner thread. When I looked at the
>>> log file on the .META RS there are no outputs at all! (INFO debug
>>> level). J-D has been helping me on this, we pretty much figured out
>>> that RegionManager.metaScanner is the culprit, because it's taking
>>> around 25 minutes to scan 8K rows. What I don't get is what the region
>>> server is actually doing during this time. There's no request at all
>>> on the cluster, no RS splits either because we just use a MR job to
>>> output HFiles and never write again.
>>> J-D has been really really helpful, but I feel like I took too much of
>>> his time. Below is the thread dump of the .META RS during the time
>>> when disables command are blocked on meta scanner, can someone help me
>>> figure out what the server is doing, is it running any thread at all?
>>> Thank you!
>>> http://pastebin.com/CZQAywq3

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