<html><head><style type="text/css"><!-- DIV {margin:0px} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">Sorry Nigel, I just started using this SBC account and didn't see these getting stuck in my spam folder until now...<br><br>To answer your question about the garbage collection issues, I've still seen many posts about garbage collection in Java 1.5. In fact, there is a known garbage collection bug in JDK1.5 that is not scheduled to be fixed until 1.5_08.<br><br>Also, despite the performance improvements (I've read of people using 12GB heap sizes on 64bit machines, but have no way to verify this), the system still spends a large amount of time processing the memory. I'm working on a project now that involves a BEA server using the Sun 1.4 JDK and a full GC of a 400MB heap is still taking about 1.0 - 1.5 seconds. From
what I've read, there are two approaches to tuning GC--the first is to setup the system to perform frequent, but short (low pause) collections (i.e. using a small heap) and the other is to tune the system using infrequent but long collections (i.e., using a large heap.) The route taken depends on the application.<br><br>Justin<br><br><div style="font-family: times new roman,new york,times,serif; font-size: 12pt;">----- Original Message ----<br>From: Nigel Kersten <nigel@cofa.unsw.edu.au><br>To: The OpenCms mailing list <opencms-dev@opencms.org><br>Sent: Friday, June 16, 2006 7:32:28 AM<br>Subject: Re: [opencms] [opencms-dev] Optimizing OpenCMS performance.<br><br><div><br>On 16/06/2006, at 9:24 PM, <justin.spies@sbcglobal.net> <br><justin.spies@sbcglobal.net> wrote:<br><br>> Having such a large VM configured can cause garbage collection <br>> issues, which lead to performance problems. I'm not sure that
is <br>> the problem here, however to find out, you can use the following VM <br>> options:<br>><br>> -verbose:gc -XX:+PrintGCTimeStamps -XX:+PrintGCDetails -Xloggc:"C: <br>> \garbage.log"<br>><br>><br>> Obviously you'll want to change the -Xloggc: value to a file that <br>> matches one on your file system. With as large of a VM as you <br>> have, it is possible that the system is causing long pauses to <br>> collect a large amount of garbage objects. Look for entries where <br>> the system does a full garbage collection and note how long they <br>> take and how far apart they are spaced.<br><br>Thank you very much Justin.<br><br>I had come across mention of this, but also that garbage collection <br>issues like this shouldn't be a problem with Tomcat 5.5 and Java 1.5, <br>does that seem right to you?<br><br>I did
test with a wide range of max values, and this cpu usage issue <br>cropped up irrespective of those settings.<br><br>Thanks for the debug info, I'll grab that.<br><br>-- <br>Nigel Kersten [Senior Technical Officer]<br>College of Fine Arts, University of NSW, Australia.<br>CRICOS Provider Code: 00098G<br><br><br><br><br>_______________________________________________<br>This mail is sent to you from the opencms-dev mailing list<br>To change your list options, or to unsubscribe from the list, please visit<br><a target="_blank" href="http://lists.opencms.org/mailman/listinfo/opencms-dev">http://lists.opencms.org/mailman/listinfo/opencms-dev</a><br></div></div><br></div></div></body></html>