I need to increase the default java heap size to get OpenNMS Linkd service running smoothly, and fortunately I have 4/5 of my total installed memory free at any given time even when their is maximum load on the server. still java is not performing to it's bast. hence I need to increase the default java heap size.

Can anyone tell me how to do it?

I'm using Ubuntu 12.04 lts & total memory installed is 16 GB out of which generally 2GB to 4GB is used.

I have already checked below questions and they did not help me resolve my issue.

1. How to increase memory allocated to java? java.lang.OutOfMemoryError: Java heap space




2. Comparing Virtual Memory Size with Resident Size




3. How to increase memory allocated to java? java.lang.OutOfMemoryError: Java heap space

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