Heavy load during web method call

[pio1k]

Hello everyone!

I have a web service with couple web methods. Those methods are calling quite often (average is about one call of each method per 10 seconds) by .NET client application. After few days of working I checked in JBoss Web Console statistics of calling of those methods. One of them has got average time of call equals about 300 milliseconds but maximum call time is over 70 minutes! I also noticed that when call of this method is very long my CPU is 100% load for all call time.

Maybe someone has got similar problem? My quest is that maybe garbage collector turn on when call was so long.

I'm using:
1) Java 1.5_0_15
2) JBoss 4.2.3
3) -XX:+UseConcMarkSweepGC -XX:+UseParNewGC options for garbage colletor

Regards,
Piter

[peterj]

The CMS collector, which you have turned on, needs lots of memory. If the CMS collector ever gets behind in cleaning the tenured generation of the heap, a very expensive "stop the world" collection takes place. I once forced the CMS collector to get behind on a particular app and the garbage collection took around 5 minutes (using the standard collector a Full GC on that same app takes about 2 seconds).

Also, do you have only one CPU? Never use the CMS collector when you have only a single CPU.

Of course, without gathering any GC data, it is all speculation. What data have you gathered so far?

[pio1k]

I have CPU with two cores - is it enough?

I have to turn on logging of GC data.

[peterj]

2 cores is adequate, but you have to realize that while the GC is running only one of the cores will be available for the app to use.

For monitoring GC, see my presentation at http://www.cecmg.de/doc/tagung_2007/agenda07/24-mai/2b3-peter-johnson/index.html