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From aaron morton <aa...@thelastpickle.com>
Subject Re: GCInspector info messages in cassandra log
Date Tue, 14 Aug 2012 10:22:21 GMT
There are a couple of steps you can take if compaction is causing GC. 

- if you have a lot of wide rows consider reducing the in_memory_compaction_limit_in_mb yaml
setting. This will slow down compaction but will reduce the memory usage. 

- reduce concurrent_compactors 

Both of these may slow down compaction. Once you have GC under control you may want to play
with memory settings.

Hope that helps.  
-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 14/08/2012, at 4:45 PM, Tamar Fraenkel <tamar@tok-media.com> wrote:

> Hi!
> I have 3 nodes ring running on Amazon EC2.
> About once a week I see in the logs compaction messages and around the same time info
messages about GC (see below) that I think means it is taking too long and happening too often.
> 
> Does it mean I have to reduce my cache size?
> Thanks,
> Tamar
> 
>  INFO [ScheduledTasks:1] 2012-08-13 12:50:57,593 GCInspector.java (line 122) GC for ParNew:
242 ms for 1 collections, 1541590352 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:27,740 GCInspector.java (line 122) GC for ParNew:
291 ms for 1 collections, 1458227032 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:29,741 GCInspector.java (line 122) GC for ParNew:
261 ms for 1 collections, 1228861368 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:30,833 GCInspector.java (line 122) GC for ParNew:
319 ms for 1 collections, 1120131360 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:32,863 GCInspector.java (line 122) GC for ParNew:
241 ms for 1 collections, 983144216 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:33,864 GCInspector.java (line 122) GC for ParNew:
215 ms for 1 collections, 967702720 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:34,964 GCInspector.java (line 122) GC for ParNew:
248 ms for 1 collections, 973803344 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:41,211 GCInspector.java (line 122) GC for ParNew:
265 ms for 1 collections, 1071933560 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:43,212 GCInspector.java (line 122) GC for ParNew:
326 ms for 1 collections, 1217367792 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:44,212 GCInspector.java (line 122) GC for ParNew:
245 ms for 1 collections, 1203481536 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:45,213 GCInspector.java (line 122) GC for ParNew:
209 ms for 1 collections, 1208819416 used; max is 1937768448
>  INFO [ScheduledTasks:1] 2012-08-13 12:51:46,237 GCInspector.java (line 122) GC for ParNew:
248 ms for 1 collections, 1338361648 used; max is 1937768448
> 
> 
> Tamar Fraenkel 
> Senior Software Engineer, TOK Media 
> 
> <tokLogo.png>
> 
> tamar@tok-media.com
> Tel:   +972 2 6409736 
> Mob:  +972 54 8356490 
> Fax:   +972 2 5612956 
> 
> 
> 


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