CODEWITHSUNDEEP
javaeclipsejvmjvm-arguments
adhg
adhg

Reputation: 10883

how to increase java memory (algorithms runs on ubuntu but not on mac; same machine configuration)

Recently I've been getting the notorious error message: OutOfMemoryError. I've a 64Bit Mac with 16GB Ram and 2X2.6 GH quad core. Getting this error message simply doesn't make sense to me because the same algoritm that I'm running (that causes this error message) is running smoothly on another machine (ubuntu 16GB Ram). 

System.out.println(java.lang.Runtime.getRuntime().maxMemory());

When I run the above code on my mac I get: 129,957,888 (without the comma of course :-))

And when running this code on the ubuntu machine I get: 1,856,700,416

Can anyone tell me how I can increase my max memory in order to run my algorithm? Thanks!

I tried to set on my eclipse: default VM arguments -Xms512m -Xmx4g, but nothing changed.

Upvotes: 3

Views: 4269

Answers (3)

andronikus
andronikus

Reputation: 4220

It looks like matt b has this one covered. I just wanted to mention that you might not want to set the max heap size as high as 4GB unless your program will really need that much. From what I understand the JVM allocates all of that memory for itself when it starts, and then uses it to run code as needed. Making it allocate that much memory might cause performance problems with other applications you're running. Instead, try stepping it up in increments of 128MB, or more if your code takes a long time to fail. Alternatively, maybe you can use a memory profiler to see how much space you actually use? I have no idea if such a thing exists.

This is probably not a problem on your setup, but for mere mortals like me, blithely allocating that much memory could be problematic.

Upvotes: 0

David M. Karr
David M. Karr

Reputation: 15235

You're going to have to elaborate. Are you running a test in Eclipse, or outside of Eclipse? Just passing the "-Xmx" parameter to Eclipse won't do what you want, even if you do it in the correct way to actually change the max mem value for Eclipse (that requires prefixing it with "-vmargs"). If you want to change the max mem value for the forked JVM that's running your algorithm, you have to change the parameters in the run configuration.

Upvotes: 1

matt b
matt b

Reputation: 140011

-Xmx and -Xms are the correct arguments to the java command to change heap size, but Eclipse has to be configured differently.

Upvotes: 6

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