On Thu, Jul 14, 2016 at 11:41 AM, André Warnier (tomcat) <a...@ice-sa.com> wrote:
> Hi Java GC gurus. > > I am coming for a bit of expert advice, not for a problem. > > At some customer site, some applications appear to react somewhat slowly > sometimes, although these are not very heavy applications, and traffic on > the site is also not very high. > > Amog several other things I'm looking at, wondering if this might have > something to do with Java/Tomcat running out of memory, and perhaps doing > excessive GC's, I set up GC logging. > Below I am pasting that small Java GC log. > This is running tomcat 6 still, the java versions and tomcat JVM relevant > switches are shown in the log. > I am starting the tomcat JVM with "-Xms1024M -Xmx1024M", and no other > non-default settings regarding memory management or GC type. > > I take it that in the log below, the first number on the left is a > timestamp in "seconds , thousands of a second". > > Based on what I am seeing below, it does not appear that this Tomcat would > be at any time running short of Heap space, does it ? > The most it seems to be using below, is 153579K, when it has 1024M to play > with. > Meither does it seem to be doing excessive GC either, since these logged > GC's are separated by several thousands of seconds. > > But what does puzzle me a bit, is that each time it runs a "minor GC", it > seems to follow this almost immediately (within 1-2 ms) with a "full GC". > > Well, i'm not a GC expert by any stretch of the imagination, but i think with your PrintGC options the "GC (System.gc())" and the "Full GC (System.gc())" are the same GC. Since they're consistent at every hour, the application may be calling the System.gc You may want to check the code if you have access to it. -Tony
