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From "Geoff Hendrey" <ghend...@decarta.com>
Subject RE: scanner deadlock?
Date Mon, 12 Sep 2011 18:13:35 GMT
Hi -

I thought that as long as I specified neither -client nor -server, that
Server Class detection would automatically invoke the "-server" option.

http://download.oracle.com/javase/6/docs/technotes/guides/vm/server-clas
s.html

We are running 12-core AMD Opteron which is AMD64, so according to the
guide above, -server is selected automatically. Please let me know if
I've misunderstood this. We *definitely* want to be running hotspot!

Regarding GC: we are generating GC logs for namenode, datanode, master
and regionserver. We do see long GC from time to time. In fact, I played
with the mslab option, but didn't find significant improvement. We've
seen times on the order of a minute in these logs, and have found no way
around it (spent countless days and nights experimenting with different
GC parameters, mslab, different heap sizes, etc).

-geoff



-----Original Message-----
From: jdcryans@gmail.com [mailto:jdcryans@gmail.com] On Behalf Of
Jean-Daniel Cryans
Sent: Monday, September 12, 2011 10:55 AM
To: user@hbase.apache.org
Subject: Re: scanner deadlock?

Two other thoughts to add on top of the rest:

 - You really should also consider using HotSpot instead of OpenJDK.
 - Depending on the size of your RS's heap, the number of concurrent
scanners and if they are doing pre-caching, you may be just GCing like
mad. Did you check that?

J-D

On Mon, Sep 12, 2011 at 10:42 AM, Stack <stack@duboce.net> wrote:
> What Eric says.
>
> Sun java can find deadlocks too, the dumb ones at least.
>
> And then Todd likes this for the same job: http://www.jcarder.org/
>
> St.Ack

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