Invalid initial and maximum heap size in JVM – How to Fix

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Here is a compilation of typical mistakes when specifying the maximum and minimum heap size in Java:

Java -Xmx4056

Issue: Error occurred during initialization of VM , The size of the object heap + VM data exceeds the maximum representable size.

Since my machine has a memory capacity of 4GB, it is necessary for either -Xms or -Xmx to have a value that is equal to or greater than the size of the physical memory.

Java -Xmx1056

Problem: An error occurred while initializing the VM, incompatible minimum and maximum heap sizes were specified.

Reason: the -Xms value is greater than the -Xmx value.

Java -Xms

Problem: An error occurred while initializing the VM, Unable to allocate sufficient space for the object heap.

The same situation occurred with my friend, if you have mentioned -Xms twice instead of -Xmx, you will also encounter this error. The cause was that -Xmx was not given and only -Xms was given.

Command: java -Xms1024 M –

Problem: An error occurred while initializing the virtual machine, the initial heap size is too small.

In order to initiate the JVM, if there is a gap between 1024 and M, JVM will interpret -Xms as 1024 bytes and display an error message indicating that it is insufficient.

Another scenario when the “invalid heap size” issue comes while restarting JVM is when you configure 64 bit JVM to accept the memory of more than 4GB but it’s running on a 32-bit data model. This “invalid heap size” occurs particularly in the Solaris box where J2SE installation contains both 32 bit and 64-bit J2SE implementation.

On other platforms such as Windows and Linux, there are separate installations of 32-bit and 64-bit JVM. If either -d32 or -d64 is not specified, the 64-bit JVM installed on Solaris machines operates with a 32-bit architecture, which does not support a Maximum heap size of 4GB, resulting in an “invalid heap size” error.

You can resolve this issue by running JVM Solaris with the -d64 command-line option, which allows the use of model data in 64-bit.

public class HelloWorld{
 public static void main(String args[]){
 System.out.println("HelloWorld to Java");
 }
}

$ test@nykdev32:~ java -version
java version "1.6.0_14"
Java(TM) SE Runtime Environment (build 1.6.0_14-b08)
Java HotSpot(TM) Server VM (build 14.0-b16, mixed mode)
$ test@nykdev32:~ java -Xmx4096M HelloWorld
Invalid maximum heap size: -Xmx4096M
The specified size exceeds the maximum representable size.
Could not create the Java virtual machine.
$ test@nykdev32:~ java -d64 -Xmx4096M HelloWorld
HelloWorld to Java

If you run your Java program from the command line, instead of running it on the virtual Java machine in Eclipse, you will receive an error message saying that you cannot create the virtual Java machine. Furthermore, if you encounter an invalid heap error, you will also receive a message stating that you could not create the virtual Java machine.

Regarding the default heap size calculation in Java, there are significant changes in how the JVM calculates it in Java update 6, version 18. This applies to both the server and client modes of the JVM on 64-bit and 32-bit machines.

1) The initial heap space and maximum heap space are increased for enhanced performance.

2) The default maximum heap space is half of the physical memory capacity, up to 192 bytes, and one-fourth of the physical memory for a capacity up to 1G. Therefore, for a 1G machine, the maximum heap size is 256MB. The maximum heap size will not be utilized until the program generates enough objects to occupy the initial heap space, which will be significantly smaller, but at least 8MB or 1/64th of the physical memory capacity, up to 1G. For capacities up to 1G, the physical memory size is half of the default maximum heap space, which is 192 bytes, and one-fourth of the physical memory. The maximum heap size for a 1G machine is 256MB. The maximum heap size will only be used once the program generates enough objects to fill the initial heap space. The minimum requirement for the initial heap space is at least 8MB or 1/64th of the physical memory capacity, up to 1G, and it will be significantly smaller.

3) The default maximum heap space for the Server Java virtual machine is 1G when there is 4GB of physical memory on a 32-bit JVM. In the case of a 64-bit JVM, the default maximum heap space is 32G for a physical memory of 128GB.

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