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.doll...@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
