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I have created a java application and many users use it. I have bundled the application in an exe file, where it is being run using this command :

java -jar -Xms256m -Xmx1024m MyApplication.jar

I am using this high "-Xmx" value because sometimes the application may need high memory to work or it may cause "Out of memory" error.

The application runs just fine for me, as i have 3GB Rams, but many other users get the error "Could not create the Java virtual machine" at startup because they have low memory: 1.5GB, or 2GB.

I am stuck here between the 2 errors "Out of memory" and "Could not create the Java virtual machine" !!

Is there a java parameter to reserve 1024 memory if this memory is available, and if not then reserve the maximum memory it can when needed ?

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  • Provide the OS(Windows/linux, 64bit/32bit) and Java(64bit/32bit) versions to make the question specific. Commented Sep 13, 2012 at 13:07
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    On 32-bit windows machines there are severe limitations on JVM size. Use 64-bit Windows or use Linux. Commented Sep 13, 2012 at 13:08

3 Answers 3

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Either you need 1 GB or you don't.

If you would like to use more memory if its available, I would try using the -server JVM which defaults to a maximum of 1/4 of main memory instead. It can also make long running programs faster. ;)

In your case it will make the maximum heap (not total memory) to be

1.5 GB -> 0.38 GB 2 GB -> 0.5 GB 3.5 GB -> 0.88 GB

This may be close enough. You might also consider using off heap memory as this can give you more options in terms of how you use your memory.

BTW: 4 GB of memory can cost less than $20. :P

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4 Comments

I agree here with Peter, you have to set some minimum requirements for running your application. You can most likely decrease this requirement by going through your application and determining if you can cut back any extensive memory usage. Ultimately it comes down to what your program is doing and how demanding that is, as for memory: 1-2GB is insanely low considering even the most low end of branded machines come with 4+ these days and you can buy quality desktop memory for really cheap as well. (think 16GB for $100)
I can buy 16 GB for £49 but I suspect from the memory sizes like 3.5 GB its running 32-bit Windows XP or similar.
Ah yes that makes sense for the ~3GB but for his users running around the 1GB mark eventually they have to understand that 1GB total system memory may be perfect for applications built to run on and handle needs from the 90's just won't cut it for the applications of today. As for the cost, the $100 was from a year or so ago, to see it continually declining is indeed amazing as always.
You can buy a Server with a Xeon E3 3.4 GHz and 16 GB of memory for $970.
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I don't believe there is.

The bigger problem you face is that, if you get Out Of Memory when you set the Xmx lower (i.e the same Xmx available to other user) then they will also get Out of Memory , so you haven't really helped anything by allowing them to set a lower Xmx.

I think the simple answer is that you need to set some minimum memory requirements for running your program.

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Unfortunately, this is the only practical solution that can be used.
I've actually seen a Java application that allows users to set the memory allocated manually, but i do not know how they do it: minecraftmine.org/wp-content/uploads/2012/01/Magic-Launcher.png
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The Java Virtual Machine wants a contiguous allocation of memory in windows. If the RAM is 2GB and it may not have enough contiguous block of memory of 1GB, hence the error.

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