Understanding eclipse.ini

This post is all about understanding the eclipse.ini file and troubleshooting the errors due to wrong/inappropriate usage of eclipse.ini file

What is eclipse.ini?

eclipse.ini is a text file containing command-line options that are added to the command line used when Eclipse is started

Eclipse startup is controlled by the options in $ECLIPSE_HOME/eclipse.ini. 

If $ECLIPSE_HOME is not defined, the default eclipse.ini in your Eclipse installation directory is used.

Location of eclipse.ini

Windows/Linux OS : In eclipse directory example C:\eclipse\Profiles\Eclipse 4.2 Classic\eclipse.ini

Mac OS : Eclipse.app/Contents/MacOS/eclipse.ini

eclipse.ini looks something like this

-startup plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar --launcher.library plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.100.v20110502 -product org.eclipse.epp.package.java.product --launcher.defaultAction openFile --launcher.XXMaxPermSize 256M -showsplash org.eclipse.platform --launcher.XXMaxPermSize 256m --launcher.defaultAction openFile -vm C:\Java\JDK\1.6\bin\javaw.exe -vmargs -Dosgi.requiredJavaVersion=1.5 -Xms40m -Xmx1024m

Lets understand each section of eclipse.in and how we can use these options: 

Specifying the heap space

Below are the options in eclipse.ini to specify heap space

-Xms40m

-Xmx512m

this sets the heap space to 40MB initially and a maximum of 512MB, incase you want to increase the heap space you can use the options like

-Xms256m

-Xmx1024m

this sets the heap space to 256MB initially and a maximum of 1024MB

Specifying the max PermGen size 

-XX:MaxPermSize=256m

this set the max PermGen size to 256m

Specifying the JVM

If a JVM is installed in the eclipse/jre directory, Eclipse will use it otherwise the launcher will consult the eclipse.ini file and the system path variable. 

Eclipse DOES NOT consult the JAVA_HOME environment variable. 

The most recommended way to specify a JVM for Eclipse to run in is to put startup configuration into the eclipse.ini file

Windows example: 

-vm

C:\Java\JDK\1.6\bin\javaw.exe 

This might not work on all systems. If you encounter "Java was started but returned exit code=1" error while starting the eclipse, modify the -vm argument to point to jvm.dll (exact path could be different):

-vm

C:\Development\Java\64bit\jdk1.7.0_09\jre\bin\server\jvm.dll

Linux example:

-vm

/opt/sun-jdk-1.6.0.02/bin/java

Mac OS example:

-vm

/System/Library/Frameworks/JavaVM.framework/Versions/1.6.0/Home/bin/java