Wasn't this exactly the kind of stuff that the Eclipse Memory Analyzer - donated by SAP - was supposed to fix ? A heap of that size for a still moderate number of 300 users is crazy, so either there is stuff like circular references that hog memory, or the design model is fundamentally flawed. I don't understand why ESME needs "sessions" ? How can a scaleable server be created if each user will allocate memory until some timeout. In a world of stateless browser-based UIs that's not going to work.
Time for me to look at that code ... -Michael ----- Original Message ----- From: Markus Kohler <[email protected]> To: [email protected] <[email protected]> Sent: Wed Nov 25 12:14:58 2009 Subject: Further analysis of the GC issue Hi all, the Garbage Collector issue I was talking about is reproducible. I've uploaded an annotated GC graph to http://picasaweb.google.com/lh/photo/wB-RRtb0wIVfpxJkTJPNuw?authkey=Gv1sRgCOve7LThpfvXsQE&feat=directlink I think the "LOGON" phase where I logon all the 300 users looks ok (given that probably textile formatting is involved) but the phase where just one user sends one message is certainly not looking good. I took the profiler and the result is a bit shocking. For that one message, 881.000.000 objects weighting 23,2 Gbyte where allocated (and reclaimed afterwards). My former record was 2Gbyte ;-) Fortunately I have a theory what happens, without looking into the code,yet, so take it with a grain of salt. It seems that the public time line for all users is re-rendered, because 99% of the allocations come from org.apache.esme.comet.PublicTimeline.render(). I guess all the actors for all the users are sitting there, not knowing that the user has closed the browser, because the user session has not yet expired. I wonder how we get around this with a real "push" model. If the browser would ask for updates this rendering could be done lazily. Or can we "ping" the browser and check whether it responds? On the other side. It should also not be necessary the re-render the message again and again because the result will be the same. I will send Richard some attachments. Not sure whether you will need them, they look very similar to the ones we already have. BTW, we should definitely check the use of scala.xml.XML$.loadString(java.lang.String) It's creating a new Parser each time, which is a bit costly because it allocates a new Buffer each time and also hits the disk, when searching for the name of the Java class. Greetings, Markus "The best way to predict the future is to invent it" -- Alan Kay
