-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Jon,
On 10/20/16 6:00 AM, Moore, Jon, Vodafone UK wrote: > I have a problem where our customers application server stops > working intermittently and when we check the Tomcat logs we get the > message " java.lang.OutOfMemoryError: PermGen space" but the Tomcat > service is still running, and we have to restart the Tomcat > service. I am a complete novice when it comes to Tomcat but am > expected to resolve this issue as this server is part of the Avaya > telephony solution. > > I have 2 questions please. > > 1 - What would be causing this. Are you also a Java novice as well? No judgement... I just want to adjust my level of snark appropriately :) Java has a special heap space called the "permanent generation" (a term which becomes less descriptive as time goes on) but basically all java.lang.Class objects loaded by the JVM go there. The more libraries and other stuff that gets loaded, the more space in permgen is used. The defaults for the size of permgen are often fairly small, and you may have to raise them. This is especially true for applications that use large frameworks like Spring. Raising the permgen space is almost always the right decision under normal circumstances when you get an OOME:permgen error. I would double whatever its current value is and monitor the application for a while to see if that improves things. The only situation I know of where raising the permgen size is not the right move is when there is a "classloader-pinning leak". That happens when you hot-deploy an application many times, but the old versions of the application are not undeploying cleanly. This situation is quite the rabbit-hole, so I'll stop there unless you can confirm that you do hot-deployments without restarting Tomcat and the JVM. If you instead get OOME for other reasons, it's frequently NOT the right decision to increase the heap size because it usually indicates that there is a memory leak in the application and giving it more heap just means you'll wait longer between failures. Instead, the application should be fixed to not leak memory :) > 2 - What are the default Java memory settings for Initial memory > pool, maximum memory pool size and thread stack size when the > fields are blank when you use the "Configure Tomcat" interface on > Windows. I was wondering if changing one or more of these settings > would help ? The default depends upon the JVM and the OS. > We are running Tomcat 6.0.26 on Windows Server 2008 R2 standard > and JVM version is 1.6.0_20-b02 Best way to find out for sure[1] is: C:\> java -XX:+PrintFlagsFinal -version 2>&1 | findstr HeapSize The two settings you are looking for are MaxHeapSize and InitialHeapSize. Those values are in bytes, so you'll probably have to divide by 1024 a couple of times to get at the "real" value in human-readable terms. The best way to find the default permgen size is: C:\> java -XX:+PrintFlagsFinal -version 2>&1 | findstr PermSize Hope that helps, - -chris [1] http://stackoverflow.com/questions/2915276/what-is-the-default-maximum-h eap-size-for-suns-jvm-from-java-se-6 -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQIcBAEBCAAGBQJYCPN3AAoJEBzwKT+lPKRYCXEQAK3AKioa7kRPTvs24yj+1vq6 SFo20WtjFhBrqyhSRdcvcwUjoDAIS6d6wqjDQ13v919jFRTsqCrDh9FQg1MeCWVB UJVmcV33XjTQUmqEY03YUPwOVjgQe6RJM+FJAE60werkHEEirg85gL/WamQ+QtfW C39sp2NO6kHpD7VWnBKPhToNmcy7lz2EK6Ye8aEXkn2mk2PZhJFRysgTqeJ/CChA KnUzWAqrDBM3OtHerivHuIEHhJB7+43bD9kiX7JZXDlcVkubAz6bep3m2sXO3T9O VYZs0ACKvnzuc6kqkStMcsGUeLWvYc5+xhCDNcxGhYXjrIWOaW5aS9QipZmAXze7 IoY2UC4vxyajRNuFmLeUWaeICDtYZaf/5d3wrlsbCIWF/vf2C+NpuynEidq6N6Yv pFvTqRd+ZsNEbsKaQwaHSHsfQVxtQbPlFfUlYWvu7vz+Y5xCyTSFoct2UqDcBedi Bo+vdHVoih/i9+4Zhg+Bieh5lygcoE9VS0KX2yu+4kwaaSohFoxwHcHXoD1SjXTU FDq2H+GXV/3bS/hAek+5WzQuPJC5etsqcMUfIcf8YjrDmR6BabEvQFk5p9APYV+x 7lcODhWFlF3tEOvKiIRmPuQz/d4/hR5ETo6h12g2UMsfY9ogEZF7I8SP1uNK3bpO cH97Lssd2MS5qj/Kd/m5 =JBc2 -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
