On 11/09/2015 15:43, Leo Donahue wrote: > On Fri, Sep 11, 2015 at 9:36 AM, Leo Donahue <donahu...@gmail.com> wrote: > >> Good day, >> >> I see this topic come up from time to time on the list. Can someone point >> me to what heap thrashing looks like? >> >> Googled java heap thrashing and looked at the images, but there isn't much >> to look at. >> >> I also tried googling for ventricular tachycardia to see if I could find a >> similar graph - it's close to what I'm seeing in VisualVM, but not quite. >> >> Is heap thrashing a very "closely spaced" saw tooth pattern?
If a lot of garbage is being created very quickly that is the sort of pattern I'd expect to see. > This is about as close as I can find that is similar to what I'm seeing. > On the left side of the graph, imagine the spacing so close together that > it looks like a solid blue read out in the monitor. When I stop the > webapp, the jvm adjusts itself back to normal. It's only during servicing > requests that I see the very closely spaced pattern. > > http://i.stack.imgur.com/B9oPL.png I've done some work on this with Tomcat (search the dev archives for allocation) pushing requests through it as fast as I could. I found the JVM could cope fairly well with it. Even after reducing the amount of GC generated (typically by pooling and re-using objects rather than creating new ones for every request) then the performance impact was minimal. Mark --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
