Could not reserve enough space for object heap to start JVM

Question

Just faced with strange issue. When i type

java -version

i got

Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.

.

java -Xms64m -Xmx64m -version

This command works fine

java version "1.6.0_24"
Java(TM) SE Runtime Environment (build 1.6.0_24-b07)
Java HotSpot(TM) Client VM (build 19.1-b02, mixed mode)

If i change xms, xmx to 128m, i get error again.

Using top command and free -m i can see, that i got over 192 mb free, so why i still get this error ?

Mem:    262144k total,    64760k used,   197384k free,        0k buffers
Swap:        0k total,        0k used,        0k free,        0k cached

Thank you

Solution 1

It looks like the machine you're trying to run this on has only 256 MB memory.

Maybe the JVM tries to allocate a large, contiguous block of 64 MB memory. The 192 MB that you have free might be fragmented into smaller pieces, so that there is no contiguous block of 64 MB free to allocate.

Try starting your Java program with a smaller heap size, for example:

java -Xms16m ...

Solution 2

I had the same problem when using a 32 bit version of java in a 64 bit environment. When using 64 java in a 64 OS it was ok.

Solution 3

According to this post this error message means:

Heap size is larger than your computer's physical memory.

Edit: Heap is not the only memory that is reserved, I suppose. At least there are other JVM settings like PermGenSpace that ask for the memory. With heap size 128M and a PermGenSpace of 64M you already fill the space available.

Why not downsize other memory settings to free up space for the heap?

Comments

[user12384512]

Yes, my machine got only 256 mb, with -Xms16m and -Xms64m it works fine. But 64 is not enough for my needs. Can it be fixed somehow, so i can use 128 mb ?

[Jesper]

Note that -Xms sets the initial heap size (-Xmx sets the maximum heap size). Does your program really need an initial heap size of 64 MB? Why not let the JVM grow it automatically?

[user12384512]

Yes, i know. But it does not really matter. Since java -Xms16m -Xmx128m -version failed too

[Jesper]

It's going to be difficult to allocate 128 MB for the Java heap if the computer only has 256 MB RAM. The OS etc. also need memory.

[T3rm1]

I have the same problem. Using 32bit Java on a 64bit system. Starting with Xmx1024 resulted in the above error. Starting with Xmx512 works fine!

[Devrim]

I had the same problem. I was using 32bit JRE on my 64bit PC. I changed the JRE to 64bit system and my problem is solved.