Thread: How to allow Java to use more memory on Linux.

Hello, I'm trying to allow a java .jar file to use the 2gb's of memory available on my linux computer. However, I get an allocation error when using over 1024mb's on Xmx or Xms. How do I allow the system to give java the memory it needs.

an allocation error

Always copy-paste error messages. Perhaps you don't have as much memory spare as you're trying to give to Java? Are you running more than one instance of your program?

I can't paste the message as it just shuts down after loading everything. But the message is, from what I can see. "Error can't allocate memory to java".

My system has 2.5gb's of memory, but when I set -Xmx -Xms higher then 1024mb's it gives me this error. I googled this and a few people said the system was blocking it from be able to allow more then 1024mb's.

If your system can't allocate memory, it doesn't have it to spare. What command line are you using? For example this doesn't work on my PC:

java -Xms22G -version
Error occurred during initialization of VM
Could not reserve enough space for object heap

but it will run like this

java -Xms20G -version
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.1) (6b24-1.11.1-4ubuntu2)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)

It's not always obvious how much of your PC's memory is 'spare' - try to find out what value for Xms (on your system, something like Xms800M might be a good one to try) the problem starts at, let us have the output from -version, and some clue from your OS how much memory you have and how much is spare. I use 'top' to get summary memory stats on Ubuntu.

Running "top" on my linux I see that I have:

Mem: 2621440k total, 1698936k used, 922504k free,

When Java is running with it's 1024M limit. Any number higher just gives me allocation errors.

and the output of "java -version"? Are you sure you're stopping the previous one before running the next one? You should have nearly 2G free before starting java

I checked the running processes and nothing for Java was running, still when I start it I get the error Can't Allocate Memory for any value higher then 1024MB.

what is the output of "java -version"?

You can post the output of uname -a too, if you like. And confirm for us that this is a physical machine and not a virtual one.

Let me clear a few things up here, as I feel I've been a little misleading. First, my linux system is a virtual private server. Second, I'm running 32bit Ubuntu. Third, here is the information you wanted.

java version "1.6.0_22"
OpenJDK Runtime Environment (IcedTea6 1.10.6) (6b22-1.10.6-0ubuntu1)
OpenJDK Server VM (build 20.0-b11, mixed mode)

Linux server1 2.6.18-274.el5.028stab093.2 #1 SMP Tue Aug 23 16:46:17 MSD 2011 i686 athlon i386 GNU/Linux

unlimited

I hope this helps, and yes I have contacted my server provider about this and they are taking all month to get back to me. I thought it might be something Java could fix.

My application is a game server, to be specific a minecraft server. It needs this memory because everything runs off memory when you open it, if you have around 30 people playing at one time you can run out of memory very fast.

Reinstalling the operating system to Debian 6 64bit and "sun-java6-jdk" fixed the memory problem. Guess it was the 32bit operating system.

you was try linux red hat?