Monitoring tomcat permgen

Is there a tool/way to monitor the tomcat memory usage i.e. permgen to avoid getting issues like below. Yes we can increase the memory and trim up the GC, but still some monitoring would be nice. It would also be desireable to send warning emails when some critical memory consumption is reached.

java.lang.OutOfMemoryError: PermGen space
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1815)
    at org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:872)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1325)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1204)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:108)
    at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:58)
    at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:297)
    at org.apache.catalina.startup.ContextConfig.start(ContextConfig.java:1064)
    at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:261)
    at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:120)
    at org.apache.catalina.core.StandardContext.start(StandardContext.java:4238)
    at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3083)
    at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:404)
    at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1279)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1571)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1580)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1580)
    at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1560)
    at java.lang.Thread.run(Thread.java:662)

Solution

You can use one of these monitoring systems

VisualVM - http://visualvm.java.net/

JConsole - http://docs.oracle.com/javase/1.5.0/docs/guide/management/jconsole.html