There are also some other GC options:
http://java.sun.com/docs/hotspot/gc5.0/gc_tuning_5.html

The latest JVM's have a new GC that has much greater performance:
http://java.sun.com/performance/reference/whitepapers/6_performance.html#2.2
http://java.sun.com/javase/6/docs/technotes/guides/vm/par-compaction-6.html
http://java.sun.com/javase/6/webnotes/6u14.html

Axton Grams

The opinions, statements, and/or suggested courses of action expressed in
this E-mail do not necessarily reflect those of BMC Software, Inc.  My
voluntary participation in this forum is not intended to convey a role as a
spokesperson, liaison or public relations representative for BMC Software,
Inc.

On Wed, Jul 15, 2009 at 7:25 PM, Joe DeSouza<joe_rem...@yahoo.com> wrote:
> **
> Hi Joe,
>
> This is done in the startup of Tomcat by including a startup paramter for
> java:
> -Xincgc
> along with the startup memory and max memory that is defined.
>
> If you are on UNIX you will need to modify your startup.sh file where you
> have these lines:
> JAVA_OPTS="$JAVA_OPTS -Xms1536m"; export JAVA_OPTS
> JAVA_OPTS="$JAVA_OPTS -Xmx2560m"; export JAVA_OPTS
> to something like
>
> JAVA_OPTS="$JAVA_OPTS -Xms1536m"; export JAVA_OPTS
> JAVA_OPTS="$JAVA_OPTS -Xmx2560m -Xincgc"; export JAVA_OPTS
>
> Restart Tomcat after that and then your process should look something
like:
> aradmin   3984     1 70 08:09 pts/1    00:00:11
> /apps/ar/jre1.6.0_13/bin/java -Xms1536m -Xmx2560m -Xincgc
> -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
>
-Djava.util.logging.config.file=/apps/ar/tomcat-5.5.25/conf/logging.properties
> -Djava.endorsed.dirs=/apps/ar/tomcat-5.5.25/common/endorsed -classpath
>
:/apps/ar/tomcat-5.5.25/bin/bootstrap.jar:/apps/ar/tomcat-5.5.25/bin/commons-logging-api.jar
> -Dcatalina.base=/apps/ar/tomcat-5.5.25
> -Dcatalina.home=/apps/ar/tomcat-5.5.25
> -Djava.io.tmpdir=/apps/ar/tomcat-5.5.25/temp
> org.apache.catalina.startup.Bootstrap start
>
> Without the incremental garbage collection turned on your process would
look
> like:
> aradmin   3531     1  0 Jun29 ?        00:04:10
> /apps/ar/jre1.6.0_13/bin/java -Xms1536m -Xmx2560m
> -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager
>
-Djava.util.logging.config.file=/apps/ar/tomcat-5.5.25/conf/logging.properties
> -Djava.endorsed.dirs=/apps/ar/tomcat-5.5.25/common/endorsed -classpath
>
:/apps/ar/tomcat-5.5.25/bin/bootstrap.jar:/apps/ar/tomcat-5.5.25/bin/commons-logging-api.jar
> -Dcatalina.base=/apps/ar/tomcat-5.5.25
> -Dcatalina.home=/apps/ar/tomcat-5.5.25
> -Djava.io.tmpdir=/apps/ar/tomcat-5.5.25/temp
> org.apache.catalina.startup.Bootstrap start
> Are you on UNIX or Windows? The instructions I have given is for UNIX. If
> you are on windows I think you need to modify your Java Options found in
the
> Java tab of the utility tomcat5w.exe
> Hope this helps..
>
> Joe
> ________________________________
> From: remedydon <mrohinikanth2...@gmail.com>
> To: arslist@ARSLIST.ORG
> Sent: Wednesday, July 15, 2009 7:54:14 PM
> Subject: Re: Apache Tomcat Memory Pool
>
> Hi Joe,
>
>
> "Another useful tip would be to turn on incremental garbage collection.
This
> is always good to free up unused portions of memory that haven't been used
> for a significant time interval."
>
> Where can I find this feature to turn it on ?
>
> Joe
>
> ________________________________
> From: "Begosh, Kevin" <kevin.beg...@lmco.com>
> To: arslist@ARSLIST.ORG
> Sent: Tuesday, February 3, 2009 3:14:40 PM
> Subject: Re: Apache Tomcat Memory Pool
>
> **
> Yes this does help and I am on 7.1 as well so this would help out a lot.
We
> are having those exact issue with Tomcat crashing.
>
> Kevin Begosh, RSP
> Tech Ops
> Enterprise Business Services
> 301-791-3540 Phone
> 410-422-3623 Cell
> kevin.beg...@lmco.com
>
> From:Action Request System discussion list(ARSList)
> [mailto:arsl...@arslist.org] On Behalf Of Joe DeSouza
> Sent: Tuesday, February 03, 2009 1:13 PM
> To: arslist@ARSLIST.ORG
> Subject: Re: Apache Tomcat Memory Pool
>
> **
> Thsi is more of a Tomcat setting than a 'BMC recommended' setting.
>
> The golden rule for sizing tomcat memory is to not use more than 65% to
70%
> of the available free memory before the tomcat service is started. This
> gives the server at least 30% to 35% headroom.
>
> With that in mind it is nice to have a max memory of at least around the 3
> GB mark where the usage of the servers is about average.
>
> Since you are using tomcat, if you are using Mid-Tier 7.1, I would
recommend
> to hop on the patch 006. In my experience here the earlier patches had a
> memory issue, that addresses OutOfMemory errors that cause Tomcat to crash
> which was addressed in Patch 006. Also the performance is way better as I
> have noticed that it takes a relatively short time for the server to build
> its cache after an initial restart on patch 006 (at least 5 to 10 times
> faster) than it was on lets say Patch 003. I haven't tried patches in
> between 003 and 006
>
> Hope this helps..
>
> Cheers
>
> Joe
>
>
> ________________________________
>
> From:"Begosh, Kevin" <kevin.beg...@lmco.com>
> To: arslist@ARSLIST.ORG
> Sent: Tuesday, February 3, 2009 12:53:46 PM
> Subject: Apache Tomcat Memory Pool
>
> **
> Does anyone know what the BMC recommended or what the best settings are
for
> the Apache Tomcat memory pool for the Mid Tier.  We are windows 2003 and
we
> have two mid tiers that are load balanced.
>
> Kevin Begosh, RSP
> Tech Ops
> Enterprise Business Services
> 301-791-3540 Phone
> 410-422-3623 Cell
> kevin.beg...@lmco.com
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