While parsing a heap dump in eclipse sometimes it throws Out of Java Heap Space error. This basically is because of a large file  (5 GB+) I was trying to parse and eclipse was started with only, see below, in most cases this was ok but it kept failing for a large file.

-vmargs
-Dosgi.requiredJavaVersion=1.7
-Xms256m
-Xmx2024m

To resolve this find the eclipse.ini in your eclipse install location, open it with a text editor and change the -vmargs,

-vmargs
-Dosgi.requiredJavaVersion=1.7
-Xms256m
-Xmx3024m

File Location.

eclipse1