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From "Howard W. Smith, Jr." <smithh032...@gmail.com>
Subject Re: RE : Tomcat 6.0.35 Crashed again
Date Thu, 11 Apr 2013 15:40:46 GMT
On Thu, Apr 11, 2013 at 10:41 AM, Mark H. Wood <mwood@iupui.edu> wrote:

> Really, no one else can tell you what settings to use.  The best we
> can hope for is some accepted rules of thumb *as starting points* for
> further tuning.
>
>
+1 to Dan, Neven, and Mark's responses. Please consider-or-do 'everything'
that they mentioned/recommended.

I did want to share my java settings for my
currently-considered-a-low-scale JSF web app running on Windows Server 2008
R2 64bit server with 32GB RAM.

-XX:HeapDumpPath=D:\apache-tomee-plus-1.6.0-SNAPSHOT\temp
-XX:+HeapDumpOnOutOfMemoryError
-Djava.awt.headless=true
-Dcom.sun.management.jmxremote.port=422
-Dcom.sun.management.jmxremote.ssl=false
-Dcom.sun.management.jmxremote.authenticate=false
-Xms1024m
-Xmx1024m
-XX:MaxPermSize=384m
-XX:+UseTLAB
-XX:+UseConcMarkSweepGC
-XX:+CMSClassUnloadingEnabled

I am very pleased with the GC performance of my app, and I do like to
monitor the performance of the app via JMX remote connection via Java
Visual VM. My app runs between 200m to 500m, but I am keeping Xms/Xmx=1024m
just to see if I ever get an OOME; so far, so good (never experienced an
OOME), but recently, I did experience some unexpected/unwanted behavior
with one of my @Schedule processes which was attempting to sync some data
from database to/with Google Calendar, and google Calendar service returned
google calendar error 503, and I recognized that the memory got up to 500m,
and the google calendar error 503 did not resolve itself over an hour
(@Schedule executes every 2 to 4 minutes, if error occurs, then data is
appended to the queue for later retry attempt). I never seen that behavior
and I don't know if I will see it again; i wish I would have done a 'heap
dump' instead of a 'stop' tomee/tomcat. Everyday, I listen and read these
questions/responses on tomcat list, and I can't believe that I forgot to do
a 'heap dump'. :(

Also, please note that I occasionally stop-deploy-and-start tomee/tomcat
almost-on-a-daily-basis to deploy new app-or-configuration-or-library
updates; also, the app or tomee (or tomcat) seem to accumlate threadlocals
over time, and if uptime is > 1 day, then I 'think' I see that memory is
not released, and I think eventually as uptime increases, then the
app/tomee/tomcat will result in OOME. :)

At any rate, hope this helps.

Howard

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