Remember that the heap is not the only place where memory is needed for the sun jdk. There is also the stacksize. (-Xss)
I'm not shure if this applies also to the IBM JDK. > -----Ursprüngliche Nachricht----- > Von: Tõnu Põld [mailto:[EMAIL PROTECTED]] > Gesendet: Mittwoch, 19. Dezember 2001 09:33 > An: 'Tomcat Users List' > Betreff: RE: Ever increasing heap size with Tomcat 3.2.3 !!! > > > Hi > > We have a similar problem with IBM JDK 1.3.0 (JIT enabled). > I suggest to debug the garbage collector (gc) by turning on > the -verbosegc > command option. The garbage collecting activity will be > written to stderr. > > In our case I suspect that it is JVM problem because the > output shows that > 90% heap is free, but still the OutOfMemoryException occurs > sometimes. The > exception occurs when the servlet application tries to > allocate big amount > of memory (5Mb). Even if we set the -Xmx128m and -Xms128m the > error occurs, > although the output shows that there is 90% (115Mb) free > space in heap. > > I suspect that the OutOfMemoryError occurs because the heap gets too > fragmented, therefore the gc can't allocate big sequential > memory area. This > makes me believe that the heap defragmentation process takes > place very > seldom. If big amount of memory is needed then it is > allocated from the end > of the heap, but if the heap size grows close to the maximum, then the > exception occurs. Does anybody know if there is a way to force the > defragmentation to occur more frequently? > > I have stress tested our application Sun JRE 1.2.2, and the > OutOfMemoryError > never occurred. > > With IBM JDK we minimized the occurrences of OutOfMemoryError > by setting the > -Xms64m and -Xmx128m. In this case the garbage collector > keeps the heap size > somewhere between min and max. Example from our log: 86% free > (92324744/107150328). But if we generate too much load then > we still get the > OutOfMemoryError. But at the moment our application doesn't > get so much > load, so the OutOfMemoryExcpetions are rare. > > Would be very thankful if anybody could confirm/explain my suspicions, > Tõnu > > > -----Original Message----- > > From: Hawkins, Keith (Keith) [mailto:[EMAIL PROTECTED]] > > Sent: Tuesday, December 18, 2001 7:34 PM > > To: [EMAIL PROTECTED]; tomcat-user > > Subject: Ever increasing heap size with Tomcat 3.2.3 !!! > > > > > > > > Hello, > > > > Before my manager insists that we switch to JRun, can any of > > the Tomcat > > developers help with a problem of an ever increasing heap > size of the > > Tomcat java.exe. ?? (We are running Tomcat 3.2.3 and > > JRE1.3.1. and the > > IIS redirector) > > > > We are running a load test using LoadRunner scripts on some JSP and > > servlets that are running under Tomcat. The load is not all > > that heavy > > but the heap size of the Tomcat java.exe process keeps growing and > > growing. We modified the java command line to start with > -Xmx128m to > > allow 128 MB of heap but we still max out after a day or > so. We even > > modified one of our servlets to create a thread that runs > > Runtime.gc() > > every 30 seconds. The LoadRunner scripts just keep logging > > in the same > > 5 people via our authentication servlet so you would think > memory use > > would level out at some point. > > > > Nothing we do seems to keep the heap size from growing. > > > > Are there known issues with Tomcat and heap size?? > > > > Doing a web search revealed numerous posts with people > having similar > > problems so I believe there is a problem. The standard > > response these > > people receive is to increase the heap size via -Xmx But > that seems > > like a band-aid rather than a real solution. That just delays the > > inevitable. > > > > Any insight as to how to keep the Tomcat process from > > grabbing more and > > more memory would be appreciated. > > > > Thanks, > > Keith > > > > > > > > > > > > > > > > > > -- > To unsubscribe: <mailto:[EMAIL PROTECTED]> > For additional commands: <mailto:[EMAIL PROTECTED]> > Troubles with the list: <mailto:[EMAIL PROTECTED]> > > > -- To unsubscribe: <mailto:[EMAIL PROTECTED]> For additional commands: <mailto:[EMAIL PROTECTED]> Troubles with the list: <mailto:[EMAIL PROTECTED]>
