[HTML]my CMS incremental duty cycle can't be controll by GC parameter settings

Thu Aug 30 01:03:57 PDT 2012

Bond --

On Wed, Aug 29, 2012 at 7:40 PM, Bond Chen <Bond.Chen at lombardrisk.com>wrote:

>  Dear All & Sri,
> Our application have encountered very long GC pause, from the GC analysis,
> I found the CMS takes 20-30 minutes to get finished by the value of
> icms_dc=1230 seconds, so the solution is to reduce this value, to let CMS
> finished ASAP, by reading a doc on oracle website about the CMS
> incremental mode, I want to have a concept demonstration test, but the
> result confusing me.
>

Not really. If you want the CMS cycled to finish as soon as possible you
should increase the duty cycle, not decrease it. (The idea is that the
duty-cycle defines the %ge of "concurrent time" that the ICMS thread will
be eligible to run.)

    -XX:CMSIncrementalDutyCycle=50

will, for example, let it run 50% of the time between two scavenges.

Then, you have to turn off the automatic duty-cycle control that ICMS does,
if you want  to maintain that duty cycle value whenever ICMS runs:-

  -XX:-CMSIncrementalPacing

I believe the min value sets a lower bound on the duty-cycle when
incremental pacing is on. It just sets a floor under which the duty-cycle
will never go.
Yes, I know, it's kind of asymmetric, and I can't recall the thinking
behind that, but it should be possible, i guess to bound the cycle between
two values
if you really wanted to make that modification. Ah, now I remember... the
idea is that concurrent mode failure is bad, so escalating the duty-cycle
to as much as 100%
should be permitted rather than bound it from above, lose the race and
cause a concurrent mode failure.

Here's the set of relevant options:-

$ java -XX:+PrintFlagsFinal -version | grep CMSIncremental
    uintx CMSIncrementalDutyCycle                   = 10
{product}
    uintx CMSIncrementalDutyCycleMin                = 0
{product}
     bool CMSIncrementalMode                        = false
{product}
    uintx CMSIncrementalOffset                      = 0
{product}
     bool CMSIncrementalPacing                      = true
{product}
    uintx CMSIncrementalSafetyFactor                = 10
{product}
java version "1.7.0_05"
Java(TM) SE Runtime Environment (build 1.7.0_05-b05)
Java HotSpot(TM) 64-Bit Server VM (build 23.1-b03, mixed mode)

-- ramki

>
> *1)I have the set 3 CMS incremental parameters:*
>  -XX:+CMSIncrementalMode -XX:CMSIncrementalDutyCycleMin=0
> -XX:CMSIncrementalDutyCycle=3
>
>    My expectation is:
>      the icms_dc value in the gc log should be in range 0-3
>
>    Actual results:
>      the icms_dc value are out of the range
>
>
>
>
> *2)All vm options:*
> VM arguments: -Dprogram.name=run.sh -Xms6072M -Xmx6072M -XX:PermSize=512m
> -XX:MaxPermSize=512m -Xss1024k -XX:+UseParNewGC -XX:+UseConcMarkSweepGC
> -XX:+CMSParallelRemarkEnabled -XX:+UseTLAB -XX:+CMSIncrementalMode
> -XX:ParallelGCThreads=6 -XX:CMSIncrementalDutyCycleMin=0
> -XX:CMSIncrementalDutyCycle=3 -XX:MaxTenuringThreshold=32
> -XX:+PrintTenuringDistribution -XX:CMSInitiatingOccupancyFraction=50
> -Xmn1700m -XX:+UseLargePages -XX:LargePageSizeInBytes=64k
> -XX:+UseCMSInitiatingOccupancyOnly -XX:+PrintGCDetails
> -XX:+PrintGCApplicationStoppedTime -Xloggc:./gc_10_20120902171712.log
> -Dsun.rmi.dgc.server.gcInterval=18000000
> -Dsun.rmi.dgc.client.gcInterval=18000000 -verbose:gc
> -Djava.library.path=/export/home/test/server/colline/cluster/jboss/server/2011.2.0.0.3/lib/valuation-lib:/export/home/test/server/colline/cluster/jboss/server/2011.2.0.0.3/firmament
> -Djava.endorsed.dirs=/export/home/test/server/colline/cluster/jboss/lib/endorsed
> -Djavax.management.builder.initial=org.jboss.system.server.jmx.MBeanServerBuilderImpl
> -Djboss.platform.mbeanserver -Dcom.sun.management.jmxremote.port=1234
> -Dcom.sun.management.jmxremote.authenticate=false
> -XX:+ExplicitGCInvokesConcurrent -XX:+PrintTenuringDistribution
> -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -XX:+PrintHeapAtGC
> -XX:+PrintPromotionFailure -XX:PrintFLSStatistics=2
> -Djboss.cluster.number=4 -Djboss.cluster.monitor.switch=y
> -Djboss.messaging.groupname=MessagingPostOffice -Djboss.partition.name=UATPartition_RH
> -Djboss.messaging.serverpeerid=10 -Djboss.web.lb.nodeid=nodee
> -Djboss.home.dir=/export/home/test/server/colline/cluster/jboss -
> Djboss.profile.name=2011.2.0.0.3 -Djboss.cluster.node1.addr=172.20.30.8
> -Djboss.cluster.node2.addr=172.20.30.11
> -Djboss.cluster.node3.addr=172.20.30.16
> -Djboss.cluster.node4.addr=172.20.30.10 -Djboss.cluster.port_hacluster=7800
> -Djboss.cluster.port_jbmdata=7900 -Djboss.cluster.port_jbmcontrol=7910
> -Djboss.cluster.port_invalidationcache=7920
> -Djboss.cluster.port_replicationcache=7930
> -Djboss.messaging.consumer_count=3 -Djboss.jndi.port=1099
> -Djboss.hajndi.port=1100
> -Dcollateral_config=/export/home/test/server/colline/cluster/bin/collateral.properties
> -DIGNORE_FQN=/marketdata/FxRates,/marketdata/EODFxRates
> -Ddatasource.min.pool.size=5 -Ddatasource.max.pool.size=150
> -Djboss.partition.udpGroup=230.1.0.4
> -Dcom.sun.management.jmxremote.port=5004
> -Dcom.sun.management.jmxremote.ssl=false
> -Dcom.sun.management.jmxremote.authenticate=false
> -Djavax.management.builder.initial=org.jboss.system.server.jmx.MBeanServerBuilderImpl
> -Djboss.platform.mbeanserver
> -Djava.endorsed.dirs=/export/home/test/server/colline/cluster/jboss/lib/endorsed
>
>
>
>
> *3)GC logs:*
> -bash-3.00$ cat gc_10_20120902004701.log |grep icms
>  icms_dc=0 , 0.1387250 secs] [Times: user=0.35 sys=0.20, real=0.14 secs]
>  icms_dc=0 , 0.3590387 secs] [Times: user=0.90 sys=0.43, real=0.36 secs]
>  icms_dc=15 , 0.5206302 secs] [Times: user=1.31 sys=0.46, real=0.52 secs]
>  icms_dc=30 , 0.2350382 secs] [Times: user=0.76 sys=0.01, real=0.24 secs]
>  icms_dc=45 , 0.4883827 secs] [Times: user=1.38 sys=0.37, real=0.49 secs]
>  icms_dc=41 , 0.7013340 secs] [Times: user=0.92 sys=0.05, real=0.70 secs]
>
>
> *4)JVM version:*
> -bash-3.00$ java -version
> java version "1.6.0_21"
> Java(TM) SE Runtime Environment (build 1.6.0_21-b06)
> Java HotSpot(TM) Server VM (build 17.0-b16, mixed mode)
> -bash-3.00$ ./launch_bondGCParameter.sh
>
> Regards,
> Bond
>
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