OutOfMemoryError: Java heap space. 1) An easy way to solve OutOfMemoryError in java is to increase the maximum heap size by using JVM options "-Xmx512M", this will immediately solve your OutOfMemoryError.
lang. OutOfMemoryError: PermGen Space is a runtime error in Java which occurs when the permanent generation (PermGen) area in memory is exhausted. The PermGen area of the Java heap is used to store metadata such as class declarations, methods and object arrays.
To increase PermGen, we have the following commands: -XX:PermSize=N - sets the initial (and minimum size) of the Permanent Generation space. -XX:MaxPermSize=N - sets the maximum size of the Permanent Generation space.
In JDK 8.0 the Permanent Generation (PermGen) space has completely been removed and is kind of replaced by a new space called Metaspace.
The solution was to add these flags to JVM command line when Tomcat is started:
-XX:+CMSClassUnloadingEnabled -XX:+CMSPermGenSweepingEnabled
You can do that by shutting down the tomcat service, then going into the Tomcat/bin directory and running tomcat6w.exe. Under the "Java" tab, add the arguments to the "Java Options" box. Click "OK" and then restart the service.
If you get an error the specified service does not exist as an installed service you should run:
tomcat6w //ES//servicename
where servicename is the name of the server as viewed in services.msc
Source: orx's comment on Eric's Agile Answers.
You better try -XX:MaxPermSize=128M
rather than -XX:MaxPermGen=128M
.
I can not tell the precise use of this memory pool, but it have to do with the number of classes loaded into the JVM. (Thus enabling class unloading for tomcat can resolve the problem.) If your applications generates and compiles classes on the run it is more likely to need a memory pool bigger than the default.
App server PermGen errors that happen after multiple deployments are most likely caused by references held by the container into your old apps' classloaders. For example, using a custom log level class will cause references to be held by the app server's classloader. You can detect these inter-classloader leaks by using modern (JDK6+) JVM analysis tools such as jmap and jhat to look at which classes continue to be held in your app, and redesigning or eliminating their use. Usual suspects are databases, loggers, and other base-framework-level libraries.
See Classloader leaks: the dreaded "java.lang.OutOfMemoryError: PermGen space" exception, and especially its followup post.
Common mistakes people make is thinking that heap space and permgen space are same, which is not at all true. You could have lot of space remaining in the heap but still can run out of memory in permgen.
Common causes of OutofMemory in PermGen is ClassLoader. Whenever a class is loaded into JVM, all its meta data, along with Classloader, is kept on PermGen area and they will be garbage collected when the Classloader which loaded them is ready for garbage collection. In Case Classloader has a memory leak than all classes loaded by it will remain in memory and cause permGen outofmemory once you repeat it a couple of times. The classical example is Java.lang.OutOfMemoryError:PermGen Space in Tomcat.
Now there are two ways to solve this:
1. Find the cause of Memory Leak or if there is any memory leak.
2. Increase size of PermGen Space by using JVM param -XX:MaxPermSize
and -XX:PermSize
.
You can also check 2 Solution of Java.lang.OutOfMemoryError in Java for more details.
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