Re: [Resin-interest] class reloading / out-of-memory
I recently performed a check in one of our applications and what I found out was that many libraries we were using were not really "prepared" to be in a context that is restarted. They usually leak resources because they are developed thiking that they will be used in a JVM where a restart of the application implies a stop/start of the JVM. For example, they create threads that cannot be stopped, JDBC drivers that never clean up some resources unless you use specific calls (so when you use them through a DataSource, they are never called.), bad use of ThreadLocals... It's not that difficult to try to keep your code free of those mistakes, but then the libraries you use might have them. Good luck! D. PD: I used YourKit Java Profiler to look for leaks. Scott Ferguson escribió: > On Jul 5, 2007, at 7:19 AM, Shane Cruz wrote: > >> That could be related to a common classloader memory leak. See this >> article for more information: >> >> http://blogs.sun.com/fkieviet/entry/classloader_leaks_the_dreaded_java > > That page is misleading, by the way, so I don't like it as a general > article. (The description of the underlying problem is correct.) > > It implies that the problem is in application code for stupidly using > Level. "Perhaps it's really your fault." In that example, it's not > the application's fault at all. It's a JDK bug. The specific > problem on that page is that the JDK's implementation of Level is > buggy. There's no way for you to know that without someone telling > you, so I can't see how that's "your fault." > > If you're interested in the reasons why Level is buggy, the article > is fine. > > You'd need a profiler to track the problem down (Resin's admin > profiler doesn't provide enough detail for this. jhat might work, > but it's a bit ugly.) > > Things to check: > >1) singletons/static fields at a parent classloader (e.g. system > classpath or host), especially caching stuff. > >2) ThreadLocal > > For example, if you put struts.jar in resin/lib, it's possible that > something like struts.jar has caching code that's not properly > classloader-aware. If you move struts.jar into WEB-INF/lib (or resin/ > ext-webapp), the problem might disappear (because the cache is no > longer at a parent level.) > > -- Scott > >> -----Original Message- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of Jan Kriesten >> Sent: Thursday, July 05, 2007 6:16 AM >> To: General Discussion for the Resin application server >> Subject: [Resin-interest] class reloading / out-of-memory >> >> >> hi, >> >> i have the following out-of-memory error when changing a class file >> of a >> web-app >> and the web-app is re-inited: >> >> ---8<--- >> java.lang.OutOfMemoryError: PermGen space >> at java.lang.ClassLoader.defineClass1(Native Method) >> at java.lang.ClassLoader.defineClass(ClassLoader.java:620) >> at >> java.security.SecureClassLoader.defineClass(SecureClassLoader.java: >> 124) >> at >> com.caucho.loader.DynamicClassLoader.loadClass >> (DynamicClassLoader.java:1 >> 329) >> at >> com.caucho.loader.DynamicClassLoader.findClass >> (DynamicClassLoader.java:1 >> 199) >> at >> com.caucho.loader.DynamicClassLoader.loadClass >> (DynamicClassLoader.java:1 >> 119) >> at >> com.caucho.loader.DynamicClassLoader.loadClass >> (DynamicClassLoader.java:1 >> 068) >> at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) >> ---8<--- >> >> this regularly happens after the app is reloaded for the 5th or 6th >> time. >> >> the admin service works without a flaw and indicates that there should >> be enough >> free memory: >> >> Total memory:122.42Meg >> Free memory: 56.45Meg >> >> any hints where to look? >> >> i'm using resin 3.1.1 and jdk 1.6 >> >> best regards, --- jan. ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest
Re: [Resin-interest] class reloading / out-of-memory
I get the same thing on my box. It does seem like something's leaking. I'm offline now but will check out the article soon. Thanks Shane. Tony On 5-Jul-07, at 10:19 AM, Shane Cruz wrote: > > That could be related to a common classloader memory leak. See this > article for more information: > > http://blogs.sun.com/fkieviet/entry/classloader_leaks_the_dreaded_java > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jan Kriesten > Sent: Thursday, July 05, 2007 6:16 AM > To: General Discussion for the Resin application server > Subject: [Resin-interest] class reloading / out-of-memory > > > hi, > > i have the following out-of-memory error when changing a class file > of a > web-app > and the web-app is re-inited: > > ---8<--- > java.lang.OutOfMemoryError: PermGen space > at java.lang.ClassLoader.defineClass1(Native Method) > at java.lang.ClassLoader.defineClass(ClassLoader.java:620) > at > java.security.SecureClassLoader.defineClass(SecureClassLoader.java: > 124) > at > com.caucho.loader.DynamicClassLoader.loadClass > (DynamicClassLoader.java:1 > 329) > at > com.caucho.loader.DynamicClassLoader.findClass > (DynamicClassLoader.java:1 > 199) > at > com.caucho.loader.DynamicClassLoader.loadClass > (DynamicClassLoader.java:1 > 119) > at > com.caucho.loader.DynamicClassLoader.loadClass > (DynamicClassLoader.java:1 > 068) > at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) > ---8<--- > > this regularly happens after the app is reloaded for the 5th or 6th > time. > > the admin service works without a flaw and indicates that there should > be enough > free memory: > > Total memory: 122.42Meg > Free memory: 56.45Meg > > any hints where to look? > > i'm using resin 3.1.1 and jdk 1.6 > > best regards, --- jan. > > > > > ___ > resin-interest mailing list > resin-interest@caucho.com > http://maillist.caucho.com/mailman/listinfo/resin-interest > > > ___ > resin-interest mailing list > resin-interest@caucho.com > http://maillist.caucho.com/mailman/listinfo/resin-interest ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest
Re: [Resin-interest] class reloading / out-of-memory
On Jul 5, 2007, at 7:19 AM, Shane Cruz wrote: > That could be related to a common classloader memory leak. See this > article for more information: > > http://blogs.sun.com/fkieviet/entry/classloader_leaks_the_dreaded_java That page is misleading, by the way, so I don't like it as a general article. (The description of the underlying problem is correct.) It implies that the problem is in application code for stupidly using Level. "Perhaps it's really your fault." In that example, it's not the application's fault at all. It's a JDK bug. The specific problem on that page is that the JDK's implementation of Level is buggy. There's no way for you to know that without someone telling you, so I can't see how that's "your fault." If you're interested in the reasons why Level is buggy, the article is fine. You'd need a profiler to track the problem down (Resin's admin profiler doesn't provide enough detail for this. jhat might work, but it's a bit ugly.) Things to check: 1) singletons/static fields at a parent classloader (e.g. system classpath or host), especially caching stuff. 2) ThreadLocal For example, if you put struts.jar in resin/lib, it's possible that something like struts.jar has caching code that's not properly classloader-aware. If you move struts.jar into WEB-INF/lib (or resin/ ext-webapp), the problem might disappear (because the cache is no longer at a parent level.) -- Scott > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Jan Kriesten > Sent: Thursday, July 05, 2007 6:16 AM > To: General Discussion for the Resin application server > Subject: [Resin-interest] class reloading / out-of-memory > > > hi, > > i have the following out-of-memory error when changing a class file > of a > web-app > and the web-app is re-inited: > > ---8<--- > java.lang.OutOfMemoryError: PermGen space > at java.lang.ClassLoader.defineClass1(Native Method) > at java.lang.ClassLoader.defineClass(ClassLoader.java:620) > at > java.security.SecureClassLoader.defineClass(SecureClassLoader.java: > 124) > at > com.caucho.loader.DynamicClassLoader.loadClass > (DynamicClassLoader.java:1 > 329) > at > com.caucho.loader.DynamicClassLoader.findClass > (DynamicClassLoader.java:1 > 199) > at > com.caucho.loader.DynamicClassLoader.loadClass > (DynamicClassLoader.java:1 > 119) > at > com.caucho.loader.DynamicClassLoader.loadClass > (DynamicClassLoader.java:1 > 068) > at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) > ---8<--- > > this regularly happens after the app is reloaded for the 5th or 6th > time. > > the admin service works without a flaw and indicates that there should > be enough > free memory: > > Total memory: 122.42Meg > Free memory: 56.45Meg > > any hints where to look? > > i'm using resin 3.1.1 and jdk 1.6 > > best regards, --- jan. > > > > > ___ > resin-interest mailing list > resin-interest@caucho.com > http://maillist.caucho.com/mailman/listinfo/resin-interest > > > ___ > resin-interest mailing list > resin-interest@caucho.com > http://maillist.caucho.com/mailman/listinfo/resin-interest ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest
Re: [Resin-interest] class reloading / out-of-memory
That could be related to a common classloader memory leak. See this article for more information: http://blogs.sun.com/fkieviet/entry/classloader_leaks_the_dreaded_java -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jan Kriesten Sent: Thursday, July 05, 2007 6:16 AM To: General Discussion for the Resin application server Subject: [Resin-interest] class reloading / out-of-memory hi, i have the following out-of-memory error when changing a class file of a web-app and the web-app is re-inited: ---8<--- java.lang.OutOfMemoryError: PermGen space at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:620) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1 329) at com.caucho.loader.DynamicClassLoader.findClass(DynamicClassLoader.java:1 199) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1 119) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1 068) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) ---8<--- this regularly happens after the app is reloaded for the 5th or 6th time. the admin service works without a flaw and indicates that there should be enough free memory: Total memory: 122.42Meg Free memory:56.45Meg any hints where to look? i'm using resin 3.1.1 and jdk 1.6 best regards, --- jan. ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest
Re: [Resin-interest] class reloading / out-of-memory
Hi, You need to set the perm size of your java virtual machine. In Resin 3.1 do this: -XX:MaxPermSize=512m S. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jan Kriesten Sent: 05 July 2007 13:16 To: General Discussion for the Resin application server Subject: [Resin-interest] class reloading / out-of-memory hi, i have the following out-of-memory error when changing a class file of a web-app and the web-app is re-inited: ---8<--- java.lang.OutOfMemoryError: PermGen space at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:620) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1329) at com.caucho.loader.DynamicClassLoader.findClass(DynamicClassLoader.java:1199) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1119) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1068) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) ---8<--- this regularly happens after the app is reloaded for the 5th or 6th time. the admin service works without a flaw and indicates that there should be enough free memory: Total memory: 122.42Meg Free memory:56.45Meg any hints where to look? i'm using resin 3.1.1 and jdk 1.6 best regards, --- jan. ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest
[Resin-interest] class reloading / out-of-memory
hi, i have the following out-of-memory error when changing a class file of a web-app and the web-app is re-inited: ---8<--- java.lang.OutOfMemoryError: PermGen space at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:620) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1329) at com.caucho.loader.DynamicClassLoader.findClass(DynamicClassLoader.java:1199) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1119) at com.caucho.loader.DynamicClassLoader.loadClass(DynamicClassLoader.java:1068) at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319) ---8<--- this regularly happens after the app is reloaded for the 5th or 6th time. the admin service works without a flaw and indicates that there should be enough free memory: Total memory: 122.42Meg Free memory:56.45Meg any hints where to look? i'm using resin 3.1.1 and jdk 1.6 best regards, --- jan. ___ resin-interest mailing list resin-interest@caucho.com http://maillist.caucho.com/mailman/listinfo/resin-interest
