Eclipse – java.lang.OutOfMemoryError: Java heap space error

In Eclipse IDE, if your program is consuming a lot of memory (loading big data) with error like java.lang.OutOfMemoryError: Java heap space error.

List<Domain> list = domainBo.findAllDomain(100000);

for(Domain domain : list){
process(domain.getDomainName());
}

It can easily hit java.lang.OutOfMemoryError: Java heap space :


Exception in thread "main" java.lang.OutOfMemoryError: Java heap spaceException in thread "main" java.lang.OutOfMemoryError: Java heap space 
at java.util.HashMap.<init>(HashMap.java:209) 
at java.util.LinkedHashMap.<init>(LinkedHashMap.java:181)

1. Solution – VM arguments

On Eclipse menu, click on Run -> Run Configurations.., select the Java application you want to run, clicks on the Arguments tab, update the VM arguments with the following options.


-Xms<size> - Set initial Java heap size
-Xmx<size> - Set maximum Java heap size

For example, -Xms512M -Xmx1024M

2. Mistake – eclipse.ini

The memory settings in eclipse.ini is allocated to Eclipse IDE only, not the program you want to run. A very common mistake is updated the heap size in eclipse.ini, and expects it to solve above out of memory problem.

Note
The Java application, Ant / Maven build scripts, or unit test cases, are run as an external tool from Eclipse, and it does not inherit the VM settings in eclipse.ini.

But, if your Eclipse IDE is always crashed by no reason, you can try to increase the heap size and perm gen in eclipse.ini.

INI File Path:

/Users/sillyhelp/Downloads/eclipse/Eclipse.app/Contents/MacOS/eclipse.ini


-startu
openFile
-showsplash
-XX:MaxPermSize=512m
-Xms512m
-Xmx1024m
-Xdock:icon=../Resources/Eclipse.icns
-XstartOnFirstThread

P.S eclipse.ini is located in the Eclipse installation folder.