Eclipse not releasing memory in Java process on Linux

My Linux server need to be able to handle 30+ eclipse instances for developers. I did a quick test of running 10 eclipse instances. The Java process associated with each eclipse initially around 200MB RSS memory, increased up to around 550MB, when more projects a开发者_运维技巧re loaded.

But Java process doesn't seem to release memory, after closing/deleting all projects within eclipse instances. I still see it uses over 550MB RSS.

How can I change Eclipse or Java settings so that memory foot print got reduced when developers closed down projects or being idle for a while?

Thanks

You may want to experiment with these (and other) JVM tuning options to make the JVM less reluctant to return memory to the OS:

-XX:MaxHeapFreeRatio Maximum percentage of heap free after GC to avoid shrinking. Default is 70. -XX:MinHeapFreeRatio Minimum percentage of heap free after GC to avoid expansion. Default is 40.

However, I suspect that you won't see the eclipse process shrink to anywhere near its initial size, since eclipse is a huge, complex application that probably lazy-loads (but does not unload, once used) a lot of classes and associated data structures.

I've never seen Java release memory.

I don't think you will get any value out of trying to get it to release memory with Eclipse, I've watched that little memory counter for YEARS and never once see the allocated memory drop.

You might try one of these. After each session, exit the JVM and restart.

Set your -Xmx lower.

Separate your instances into categories with high -Xmx and low -Xmx and let the user determine which one he wants.

As a side-thought, if it really mattered to you, you MIGHT be able to run multiple eclipse instances under one VM. It would probably be WAY too much work (man-weeks to man-years), but if you could get it right you could reduce overhead by like 150-200mb/instance. The disadvantage would be that a VM crash (Pretty rare these days) would kill everyone.

Testing this theory would be a matter of calling eclipse's main from within an existing JVM and trying to get it to display somewhere useful. The rest of the man-year is spent trying to figure out where they used evil static variables or singletons and changing them to something else.

Switch the Java to use the G1 garbage collector with the HeapFreeRatio parameters. Use these options in eclipse.ini:

-XX:+UnlockExperimentalVMOptions
-XX:+UseG1GC
-XX:MinHeapFreeRatio=5
-XX:MaxHeapFreeRatio=25

Now when Eclipse eats up more than 1 GB of RAM for a complicated operation and switched back to 300 MB after Garbage Collection the memory will be released back to the operating system.

I would suggest checking on garbage collection, setting right options or even forcing GC periodically might increase time till eclipse memory usage grows high. Following link might be useful http://www.eclipsezone.com/eclipse/forums/t93757.html