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First of all, I have a box with 8gb of ram, so I doubt total memory is the issue. This application is running fine on machines with 6gb or less.

I am trying to reserve 3GB of space using -Xmx3G under "VM Arguments" in Run Configurations in Eclipse.

Every time I try to reserve more than 1500mb, I get this error: “Error occurred during initialization of VM; Could not reserve enough space for object heap” using -Xmx3G

What is going on here?

user1212731
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16 Answers16

71

Could it be that you're using a 32-bit jvm on that machine?

Laurent
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    Sorry for the stupid question, but how would I check that? And how can I use 64-bit? – user1212731 Feb 16 '12 at 00:48
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    Actually, I just tried java -d64 -version in the command line, and it came up with 64-bit server VM. – user1212731 Feb 16 '12 at 00:51
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    Apparently Eclipse was using the 32-bit version of JRE that I had installed previously, even though the 64-bit was the latest installation. I changed the settings in Preferences --> Installed JREs to solve this issue. Thank you very much for your answer! – user1212731 Feb 16 '12 at 19:28
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    in any case, shouldnt 32 bit be enough to address 4gb? – Thomas May 24 '13 at 12:36
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    It should be, but this solves my problem. No upvote for this answer because of the lack of explanation. [This link explains how a 32bit jvm can't go over 1gb max heap space](http://javarevisited.blogspot.be/2011/05/java-heap-space-memory-size-jvm.html) – Steven Nov 20 '13 at 09:54
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    Please provide an answer in the answer, not a question – Mark W May 28 '15 at 08:36
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    @user1212731: Nothing dumb about that question! `java -version` will give you a hint. If it does *not* say `64-Bit`, assume 32-bit. – kevinarpe Oct 19 '15 at 09:49
  • @Thomas You'd think that, yes. But the 4GiB limit is for the *whole process* and not just the heap. The kernel takes a large chunk of that space. For example, on Windows, the OS maps fully *half* of that address space to itself. So you are already down to a maximum userspace memory of 2GiB. The JVM isn't memory-less, there are non-heap spaces, then you actually have to load *code* to execute and that needs to be JIT-compiled into actual code runnable by the CPU and pretty soon you find that your Java heap is limited to something like 1.5GiB. – Christopher Schultz Jul 20 '19 at 00:44
64

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: ;C:\Program Files\Java\jre6\bin;F:\JDK\bin;  

Change this to your appropriate path.

Adnan
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Mohamed Adel
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    Just a note for others. You add a SYSTEM variable, not a USER variable. I ran into this problem in Eclipse and did not have to reboot my machine after making the above changes... I only had to restart Eclipse. Thanks! – captain_jim1 Mar 22 '17 at 15:12
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    For the curious people, the -Xmx flag in _JAVA_OPTIONS specifies the maximum allowed JVM heap size. This prevents JVM from requesting unreasonable space (especially unallocatable contiguously for 32-bit machines...) – varun Feb 27 '19 at 17:23
42

This is actually not an Eclipse-specific issue; it's a general Java-on-Windows issue. It's because of how the JVM allocates memory on Windows; it insists on allocating a contiguous chunk of memory, which often Windows can't provide, even if there are enough separate chunks to satisfy the allocation request. There are utilities that will try to help Windows "defrag" its memory, which would, in theory, help this situation; but I've not really tried them in earnest so can't speak to their effectiveness. One thing that I've heard sometimes that might help is to reboot Windows and, before starting any other apps, launch the Java app that needs the big chunk of memory. If you're lucky, Windows won't have fragmented its memory space yet and Java will get the contiguous block that is asks for.

Somewhere out on the interwebs there are more technical explanations and analyses of this issue, but I don't have any references handy.

I did find this, though, which looks helpful: https://stackoverflow.com/a/497757/639520

Community
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E-Riz
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    In my case, your answer seems work. I did not restart windows but I tried closing other apps in my windows and then run java and it was able to kick up the VM. – Syed Ali Feb 16 '15 at 10:08
22

First the JRE of 32bits can't use more ~1.5Gb of ram. So if you want more, use a 64bits JRE.

Second, When a new JVM starts, this sum the -Xmx property of the all JVM that are running, and check if there is enough memory left on the system to run at their own -Xmx, if is not enough then the error occurs.

Daniel De León
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17

I was using Liferay with Tomcat server from eclipse IDE. I was stuck with this same error on click on server start up. Double click on server from eclipse. it open up Server Overview page. Updated memory arguments from -Xmx1024m -XX:MaxPermSize=256m to -Xmx512m -XX:MaxPermSize=256m. Then it was working for me.

Prathap
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Make sure that Eclipse is actually running the same JVM you think it's running. If you use java in your web browser ever, you likely have a 32-bit version floating around too that might be taking precedence if it installed or updated lately.

To be absolutely sure, I recommend adding these two lines to your eclipse.ini file at the top:

-vm 
C:/Java/jdk1.6.0_27/bin

...where on my machine C:/Java/jdk1.6.0_27/bin where the JVM I know is 64-bit is located. Be sure to have the bin folder there.

(As a bonus, on Windows 7, this also allows you to actually "pin the tab" which is why I had to do this for my own usage)

Adam Rofer
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  • The -vm argument should point to the Java executable, not just a folder. See http://wiki.eclipse.org/%C2%A0eclipse.ini#Specifying_the_JVM – E-Riz Feb 16 '12 at 15:03
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    Wrong. See this Eclipse bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=314805 – Adam Rofer Feb 16 '12 at 16:18
  • This was indeed the issue! Eclipse was using the 32-bit version of JRE that I had installed at some point. Thank you very much for the answer and leading me in the right direction! I very much appreciate it. – user1212731 Feb 16 '12 at 19:25
  • @AdamRofer, that bug is interesting, but specifically about Windows 7 and to work around a problem with pinning Eclipse to the taskbar. In general, eclipse.ini should point to the java executable, although the Equinox launcher seems to be intelligent in that it will look for a java executable if -vm points to a folder (on Windows, at least). – E-Riz Feb 16 '12 at 20:12
  • @E-Riz "should" is too strict for my taste :) Hopefully they resolve the bug without having to change the vm argument sometime. Here's more information that would be be good for them to update on their `eclipse.ini` page: http://wiki.eclipse.org/Equinox_Launcher#Finding_a_VM.2C_Using_JNI_Invocation_or_Executing_Java – Adam Rofer Feb 16 '12 at 20:41
5

This is the issue of Heap size. Edit your .bat (Batch file). It might be showing Heap size 1024. Change it to 512 Then it should work.

user1740626
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Just put # symbol in front of org.gradle.jvmargs=-Xmx1536m in gradle.properties

 # org.gradle.jvmargs=-Xmx1536m
lczapski
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Ms. Sonia
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2

I also had the same problem while using Eclipse which was 32 bit and the JVM used by it was 64 bit. When I routed the Eclipse to 32 bit JVM then it worked

AKs
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1

I know that i am a bit late, but here my answer comes:

I just installed the Java online Version from Oracle(not the offline 64-Bit one).

After having added the JAVA_HOME ENV variable, it just worked!

Hope I could help :)

Lars
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0

Probably you are trying wrong options anyways. I got a similar error with supporting error log:

Java HotSpot(TM) Client VM warning: ignoring option PermSize=32M; support was removed in 8.0
Java HotSpot(TM) Client VM warning: ignoring option MaxPermSize=128M; support was removed in 8.0

Im my case, the software did not support java 8 yet(script was using old JVM arguments) but I had had java 8 by default.

Mateva
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0

One of the reason for this issue is no memory available for Tomcat to start. Try to delete the unwanted running software from windows and restart the eclipse and tomcat.

sooribabu
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Solution is simple. No need to go deep into this issue.

If you are running on 64bit machine then follow below steps:

  • Unistall 32 bit java first (check in C:\Program Files (x86) for its existence)
  • Install the newer version JDK kit 64 bit (includes JRE)
  • Set the environment path (To avoid conflict error if you have two different 64bit JRE)
  • Check in command prompt by typing javac command.
  • Restart / Done

You can have two different Java installed but don't forgot to set path.

0

Please set JAVA_OPTS=-Xms256m -Xmx512m in environment variables, it should solve the issue, it worked for me.

vinay j
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Find out if you are using a 32bit version or 64bit version of Java. To know that use the command

java -version

The 3rd line of the output should give you if it 32bit or 64bit.

enter image description here

If it is 32bit uninstall and install a 64bit version.

Teja Goud Kandula
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I know this is a eclipse-related question, but I faced this problem in Android studio. I am posting what I did, in case someone gets this error in Android studio. First of all, I have the following line in gradle.properties

org.gradle.jvmargs=-Xmx2048m

If I remove the line, the problem is solved but this is not the proper way. What you need to do is, set the proper gradle JDK. Go to File->Settings->Build, Execution, Deployment->Build Tools-Gradle and set the Gradle JDK to something like xx java version "xx.x.xx" C:/Program Files/Android/Android Studio/jbr

Please note: This solution is applicable to Android studio only

Bibaswann Bandyopadhyay
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