Could not reserve enough space for object heap

I am getting the following exception repeatedly each time I try to run the program.

Error occurred during initialization of VM

Could not reserve enough space for object heap

Could not create the Java virtual machine.

I tried to increase my virtual memory (page size) and RAM size, but to no avail.

How can I eliminate this error?

26 Answers

Run the JVM with -XX:MaxHeapSize=512m (or any big number as you need) (or -Xmx512m for short)

This can also be caused by setting something too large on a 32-bit HotSpot vm, for example:

-Xms1536m -Xmx1536m

where this might/would work:

-Xms1336m -Xmx1336m

here is how to fix it:

  • Go to Start->Control Panel->System->Advanced(tab)->Environment Variables->System

    Variables->New: Variable name: _JAVA_OPTIONS Variable value: -Xmx512M Variable name: Path
    Variable value: %PATH%;C:Program FilesJavajre6bin;F:JDKbin;

Change this to your appropriate path.

I ran into this when using javac, and it doesn’t seem to pick up on the command line options,

-bash-3.2$ javac -Xmx256M 
Error occurred during initialization of VM
Could not reserve enough space for object heap
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

so the solution here it so set _JAVA_OPTIONS

-bash-3.2$ export _JAVA_OPTIONS="-Xmx256M"
-bash-3.2$ javac 
Picked up _JAVA_OPTIONS: -Xmx256M

And this compiles fine.

This happens to me on machines with a lot of RAM, but with lower memory ulimits. Java decides to allocate a big heap because it detects the ram in the machine, but it’s not allowed to allocate it because of ulimits.

32-bit Java requires contiguous free space in memory to run. If you specify a large heap size, there may not be so much contiguous free space in memory even if you have much more free space available than necessary.

Installing a 64-bit version of Java helps in these cases, the contiguous memory requirements only applies to 32-bit Java.

Combined with -Xmx512M use -d64 to make sure you’re running 64-bit VM. On a 64-bit machine I thought for sure I was running 64-bit virtual machine, but no. After installing 64-bit Java the -d64 option works and -Xmx allows much larger memory sizes.

java -d64 -Xmx512M mypackage.Test

I got the same error and resolved this by configuring it in the run.conf.bat

Run the JVM with the configuring run.conf.bat in Jboss5x

If free memory is not available AS you are passing in the statement then please make changes in run.conf.bat

set "JAVA_OPTS=-Xms512m -Xmx512m -XX:MaxPermSize=256m"

I had similar issues. I had installed 32 bit version of Java on a 64 bit machine.

By uninstalling that version and installing 64 bit version of Java. I was able to resolve the issue.

I know there are a lot of answers here already, but none of them helped me. In the end I opened the file /etc/elasticsearch/jvm.options and changed:




That solved it for me. Hopefully this helps someone else here.

Suppose your class is called Test in package mypackage. Run your code like this:

java -Xmx1024m mypackage.Test

This will reserve 1024 MB of heap space for your code. If you want 512 MB, you can use:

java -Xmx512m mypackage.Test

Use little m in 1024m, 512m, etc

Sometimes, this error indicates that physical memory and swap on the server actually are fully utilized!

I was seeing this problem recently on a server running RedHat Enterprise Linux 5.7 with 48 GB of RAM. I found that even just running

java -version

caused the same error, which established that the problem was not specific to my application.


cat /proc/meminfo

reported that MemFree and SwapFree were both well under 1% of the MemTotal and SwapTotal values, respectively:

MemTotal:     49300620 kB
MemFree:        146376 kB
SwapTotal:     4192956 kB
SwapFree:         1364 kB

Stopping a few other running applications on the machine brought the free memory figures up somewhat:

MemTotal:     49300620 kB
MemFree:       2908664 kB
SwapTotal:     4192956 kB
SwapFree:      1016052 kB

At this point, a new instance of Java would start up okay, and I was able to run my application.

(Obviously, for me, this was just a temporary solution; I still have an outstanding task to do a more thorough examination of the processes running on that machine to see if there’s something that can be done to reduce the nominal memory utilization levels, without having to resort to stopping applications.)

Error :

For the error, “error occurred during initialization of vm could not reserve enough space for object heap jboss”

Root Cause :

  • Improper/insufficient memory allocation to our JVM as mentioned below.

  • e.g. JAVA_OPTS=”-Xms1303m -Xmx1303m -XX:MaxPermSize=256m” in jboss-eap-6.2binstandalone.conf or “JAVA_OPTS=-Xms1G -Xmx1G -XX:MaxPermSize=256M” in jboss-eap-6.2binstandalone.conf.bat which is nothing but JVM memory allocation pool parameters.

Resolution :

  • Increase the heap size. To increase the heap size,
  • goto -> jboss-eap-6.2binstandalone.conf.bat or jboss-eap-6.2binstandalone.conf
  • change ->JAVA_OPTS=”-Xms256m -Xmx512m -XX:MaxPermSize=256m” where -Xms is Minimum heap size and -Xmx is Maximum heap size.
  • Usually its not recommanded to have same size for min and max.

  • If you are running your application from eclipse,

  • Double click on the server
  • select ‘open launch configuration’ you will be redirected to the window ‘Edit launch configuration properties’.
  • In this windown goto the tab ‘(x)=Arguments’.
  • In VM Arguments, define your heap size as mentioned below
  • “ JBoss EAP 6.1+ Runtime Server” -server -Xms256m -Xmx512m -XX:MaxPermSize=256m -Dorg.jboss.resolver.warning=true

I recently faced this issue. I have 3 java applications that start with 1024m or 1280m heap size. Java is looking at the available space in swap, and if there is not enough memory available, the jvm exits.

To resolve the issue, I had to end several programs that had a large amount of virtual memory allocated.

I was running on x86-64 linux with a 64-bit jvm.

I had right amount of memory settings but for me it was using a 64bit intellij with 32 bit jvm. Once I switched to 64 bit VM, the error was gone.

Open file in android folder.

Replace this line:




Explanation: Max limit from Gradle document:

If the requested build environment does not specify a maximum heap size, the Daemon will use up to 512MB of heap.

Assuming you have enough free memory and you setup you JVM arguments correctly, you might have a problem of memory fragmentation. Check Java maximum memory on Windows XP.

If you’re running 32bit JVM, change heap size to smaller would probabaly help. You can do this by passing args to java directly or through enviroment variables like following,

java -Xms128M -Xmx512M
JAVA_OPTS="-Xms128M -Xmx512M"

For 64bit JVM, bigger heap size like -Xms512M -Xmx1536M should work.

Run java -version or java -d32, java--d64 for Java7 to check which version you’re running.

Anyway, here is how to fix it: Go to Start->Control Panel->System->Advanced(tab)->Environment Variables->System Variables->New: Variable name: _JAVA_OPTIONS Variable value: -Xmx512M


Change the ant call as shown as below.

        **<arg value="-J-Xmx512m" />**

It worked for me.

Error occurred during initialization of VM Could not reserve enough space for 1572864KB object heap

I changed value of memory in settings.grade file 1536 to 512 and it helped

Go to Start->Control Panel->System->Advanced(tab)->Environment Variables->System Variables->New:

Variable name: _JAVA_OPTIONS
Variable value: -Xmx512M

In case you are running a java program: – run your program in a terminal using the correct command for linux it would be ‘java -jar myprogram.jar’ and add -Xms256m -Xmx512m, for instance: ‘java -jar myprogram.jar Xms256m -Xmx512m’

In case you are running a .sh script (linux, mac?) or a .bat script (windows) open the script and look for the java options if they are present and increase the memory.

If all of the above doesn’t work, check your processes (ctrl+alt+delete on windows) (ps aux on linux/mac) and kill the processes which use allot of memory and are not necessary for your operating system! => Try to re-run your program.

In CASSANDRA_HOME/bin/cassandra.bat you would find following configuration

REM JVM Opts we'll use in legacy run or installation
set JAVA_OPTS=-ea^

You can reduce 2G to some smaller number for e.g. 1G or even lesser and it should work.

Same if you are running on unix box, change in .sh file appropriately.

I got the same error and it got resolved when I deleted temp files using %temp% and restarting eclipse.

Sometimes it relates as

$ sysctl vm.overcommit_memory
vm.overcommit_memory = 2

If you set it to:

$ sysctl vm.overcommit_memory=0

It should work.

Replace -Xmx2G with -Xms512M or any greater memory size in cassandra.bat file in cassandra bin directory.

No need to do anything just chnage in POM file like below


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