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Posted to user@cassandra.apache.org by Ying Tang <iv...@gmail.com> on 2010/12/06 13:07:12 UTC
0.7.0beta3 Cassandra frequently log GC for ConcurrentMarkSweep
I hava a two node , running cassandra ,both's memory is 4G.
First i set heap size to 2G ,both run normal .
The i set heap size to 1G , the client who insert data to and read data
from cassandra began throw Read\Write Unavailable Exception . And one
cassandra node began logging GC for ConcurrentMarkSweep frequently ,every
ConcurrentMarkSweep 's time is over 5000ms.
How this happen ? Why frequently ConcurrentMarkSweep GC ,not ParNew GC?
--
Best regards,
Ivy Tang
Re: 0.7.0beta3 Cassandra frequently log GC for ConcurrentMarkSweep
Posted by Jonathan Ellis <jb...@gmail.com>.
If it's GCing frequently and each CMS is only collecting a small
fraction of the old gen, then your heap is probably too small.
(GCInspector only logs collections that take over 1s, which should
never include ParNew.)
On Mon, Dec 6, 2010 at 7:11 AM, Ying Tang <iv...@gmail.com> wrote:
> And after checking node who gc concurrentMarkSweep frequently ,it's
> OC(Current old space capacity (KB)) is 1006016.0 ,it's OU(Old space
> utilization (KB).) is also 1006016.0 ,almost all memory.
> Dose this situation imply this heap size is set too low?
>
> On Mon, Dec 6, 2010 at 8:07 PM, Ying Tang <iv...@gmail.com> wrote:
>>
>> I hava a two node , running cassandra ,both's memory is 4G.
>> First i set heap size to 2G ,both run normal .
>> The i set heap size to 1G , the client who insert data to and read data
>> from cassandra began throw Read\Write Unavailable Exception . And one
>> cassandra node began logging GC for ConcurrentMarkSweep frequently ,every
>> ConcurrentMarkSweep 's time is over 5000ms.
>> How this happen ? Why frequently ConcurrentMarkSweep GC ,not ParNew GC?
>>
>> --
>> Best regards,
>> Ivy Tang
>>
>>
>
>
>
> --
> Best regards,
> Ivy Tang
>
>
>
--
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com
Re: 0.7.0beta3 Cassandra frequently log GC for ConcurrentMarkSweep
Posted by Ying Tang <iv...@gmail.com>.
And after checking node who gc concurrentMarkSweep frequently ,it's OC(Current
old space capacity (KB)) is 1006016.0 ,it's OU(Old space utilization (KB).)
is also 1006016.0 ,almost all memory.
Dose this situation imply this heap size is set too low?
On Mon, Dec 6, 2010 at 8:07 PM, Ying Tang <iv...@gmail.com> wrote:
> I hava a two node , running cassandra ,both's memory is 4G.
> First i set heap size to 2G ,both run normal .
> The i set heap size to 1G , the client who insert data to and read data
> from cassandra began throw Read\Write Unavailable Exception . And one
> cassandra node began logging GC for ConcurrentMarkSweep frequently ,every
> ConcurrentMarkSweep 's time is over 5000ms.
> How this happen ? Why frequently ConcurrentMarkSweep GC ,not ParNew GC?
>
> --
> Best regards,
> Ivy Tang
>
>
>
>
--
Best regards,
Ivy Tang