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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: GCInspecto​r causing slow writes?
Date Tue, 28 Feb 2012 17:11:31 GMT
No, a gc pause of 100ms isn't going to cause 4s delays.  My first
guess would be backed-up requests (visible in nodetool tpstats) due to
too much random i/o (visible in iostat).

On Tue, Feb 28, 2012 at 5:44 AM, Neil Dolling <neil.dolling@gmail.com> wrote:
> When writing to Cassandra (v 1.0.7) I'm seeing ocasional delays of up to 4
> seconds. Below is from the system.log where we are seeing the delays, is
> this a result of GC and is it worth me tuning these settings in order to
> fix? If so, any suggestions? adjusting memtable_total_space_in_mb?
>
> DEBUG [ScheduledTasks:1] 2012-02-27 12:39:03,570 GCInspector.java (line 124)
> GC for ParNew: 97 ms for 1 collections, 1401494128 used; max is 8506048512
> DEBUG [WRITE-/127.0.0.1] 2012-02-27 12:39:04,323 OutboundTcpConnection.java
> (line 206) attempting to connect to /127.0.0.1
> DEBUG [RequestResponseStage:27] 2012-02-27 12:39:07,992
> ResponseVerbHandler.java (line 44) Processing response on a callback from
> 1147398@/154.4.196.76
> DEBUG [RequestResponseStage:30] 2012-02-27 12:39:07,992
> ResponseVerbHandler.java (line 44) Processing response on a callback from
> 1147403@/154.4.196.76
> DEBUG [RequestResponseStage:31] 2012-02-27 12:39:07,992
> ResponseVerbHandler.java (line 44) Processing response on a callback from
> 1147400@/154.4.196.76
> DEBUG [RequestResponseStage:25] 2012-02-27 12:39:07,992
> ResponseVerbHandler.java (line 44) Processing response on a callback from
> 1147401@/154.4.196.76
> DEBUG [RequestResponseStage:32] 2012-02-27 12:39:07,992
> ResponseVerbHandler.java (line 44) Processing response on a callback from
> 1147402@/154.4.196.76
> DEBUG [RequestResponseStage:29] 2012-02-27 12:39:07,992
> ResponseVerbHandler.java (line 44) Processing response on a callback from
> 1147399@/154.4.196.76



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

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