Overview

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 (or in the case of Mac, the Eclipse.app/Contents/MacOS directory) is used.

eclipse.ini is a text file containing command-line options that are added to the command line used when Eclipse is started up. There are many options available, please see 

Important:

1. Each option and each argument to an option must be on its own line.
2. All lines after -vmargs are passed as arguments to the JVM, so all arguments and options for eclipse must be specified before -vmargs (just like when you use arguments on the command-line)
3. Any use of -vmargs on the command-line replaces all -vmargs
    settings in the .ini file unless --launcher.appendVmargs is specified either in the .ini file or on the command-line. (doc)

By default, eclipse.ini looks something like this (the exact contents will vary based on operating system and which Eclipse package you have):

-startup
../../../plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar
--launcher.library
../../../plugins/org.eclipse.equinox.launcher.cocoa.macosx.x86_64_1.1.100.v20110502
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-vmargs
-Dosgi.requiredJavaVersion=1.5
-XX:MaxPermSize=256m
-Xms40m
-Xmx512m

Among other things, this sets the heap space to 40MB initially and a maximum of 512MB, and also specifies a maximum PermGen size of 256MB. A max heap of 512MB might be OK for some users, but it's often necessary to bump that value up for large project sets or when some third-party plugins are installed.

Specifying the JVM

One of the most recommended options to use is to specify a specific JVM for Eclipse to run on. Doing this ensures that you are absolutely certainwhich JVM Eclipse will run in and insulates you from system changes that can alter the "default" JVM for your system. Many a user has been tripped up because they thought they knew what JVM would be used by default, but they thought wrong. eclipse.ini lets you be CERTAIN.

The following examples of eclipse.ini demonstrate correct usage of the -vm option.

Note the format of the -vm option - it is important to be exact:

• The -vm option and its value (the path) must be on separate lines.
• The value must be the full absolute or relative path to the Java executable, not just to the Java home directory.
• The -vm option must occur before the -vmargs option, since everything after -vmargs is passed directly to the JVM.

Here is an example of what eclipse.ini might look like on a Windows system after you've added the -vm argument and increased the maximum heap space:

-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

Remember that the exact values will differ slightly depending on operating system and Eclipse package.

-vm value: Windows Example

This is how the -vm argument might look on Windows (your exact path to javaw.exe could be different, of course):

-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 -vmargument to point to jvm.dll (exact path could be different):

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

-vm value: Linux Example

This is how the -vm argument might look on Linux (your exact path to javacould be different, of course):

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

-vm value: Mac OS X Example

On a Mac OS X system, you can find eclipse.ini by right-clicking (or Ctrl+click) on the Eclipse executable in Finder, choose Show Package Contents, and then locate eclipse.ini in the MacOS folder under Contents.

To specify Java 6 for OS X:

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