Sometimes, an exception is thrown when you try to parse a large heap dump file.

Problem

Unable to open large hprof file, because of the exception shown below.

An internal error occurred during: "Parsing heap dump from 'D:\tmp\oom1\java_pid14164.hprof'".
Java heap space

Cause

The heap size of Eclipse Memory Analyser Tool is not enough to parse a heap dump file.

Solution

Go to Eclipse MAT home directory and edit MemoryAnalyzer.ini  file. Change -Xmx  parameter value to appropriate one. There are situations in which it’s necessary to set -Xmx  parameter value above the size of parsed heap dump file. i.e. if you try to open 4GB *.hprof and get Java heap space error, you should try to raise Xmx above 4GB:  -Xmx5g

-startup
plugins/org.eclipse.equinox.launcher_1.3.100.v20150511-1540.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.300.v20150602-1417
-vmargs
-Xmx5g

I hope it was helpful to you. If you have any questions, feel free to ask me in comments below.