What Is The Maximum Heap Size Of 32 Chip Or 64-Bit Jvm Inward Windows As Well As Linux?

Maximum heap size  for 32 flake or 64 flake JVM looks slowly to create upward one's hear yesteryear looking at addressable retentiveness infinite similar 2^32 (4GB) for 32 flake JVM together with 2^64 for 64 flake JVM. Confusion starts hither because you lot tin non actually laid 4GB equally maximum heap size for 32 flake JVM using -Xmx JVM heap options. You volition get could non create the Java virtual machine Invalid maximum heap size: -Xmx  error. There could hold upward many dissimilar argue why maximum heap infinite for JVM is less than in that place theoretical boundary together with vary from i operating organization to other e.g. dissimilar inward Windows, Linux together with Solaris. I own got seen brace of comments on my post 10 points on Java Heap Space regarding what is maximum heap infinite for Java or 32 flake JVM or 64 flake JVM together with why Windows allows alone upto 1.6G retentiveness equally maximum heap infinite etc. In this Java article, I own got collected some of the oft asked questions unopen to maximum heap space on both 32 together with 64 flake JVM together with tried to explicate them.

FAQ Maximum Java Heap Space on 32 together with 64 flake JVM

flake JVM looks slowly to create upward one's hear yesteryear looking at addressable retentiveness infinite similar What is the maximum Heap Size of 32 flake or 64-bit JVM inward Windows together with Linux?Here is listing of some confusions I own got seen on Java programmers regarding maximum heap infinite of 32 together with 64 flake Java Virtual Machines :
  1. What is maximum heap size for 32 flake JVM?  2GB or 4GB?
  2. Why my JVM non able to kickoff on windows when maximum heap infinite unopen to 1600M?
  3. Why Linux or Solaris permit to a greater extent than maximum heap size than windows for same, 32 flake JVM?
  4. Can nosotros laid to a greater extent than than 4GB equally maximum heap size for 32 flake JVM running on 64 flake or x64 operating system?
  5. What is maximum heap size for 64 flake or x64 JVM, Is it 8GB or 16GB?
  6. Can I specify to a greater extent than than 1GB equally heap infinite if physical retentiveness is less than 1GB?


If you lot besides own got similar confusion on JVM maximum heap infinite no matter whether its for your ain Java application or whatever Java spider web or application server similar Tomcat, JBoss or WebLogic, This give-and-take applies to all of them.

What is maximum heap size for 32 flake JVM?  2GB or 4GB?
This confusion comes because of sign bit, many programmer mean value inward damage of signed integer together with they mean value maximum addressable retentiveness (size of address bus) for 32 flake architecture is 2^32-1 or 2GB and this confusion is supported yesteryear fact that you lot tin non furnish maximum heap infinite equally 2GB on windows machine. But this is wrong. Memory is zero to create amongst signed or unsigned flake equally in that place is no negative retentiveness address. So theoretical boundary for maximum heap size on 32 flake JVM is 4GB together with for 64 flake JVM its 2^64.

Why JVM non able to kickoff on Windows XP when maximum heap infinite unopen to 1600M?
This work is nearly obvious on Windows platform similar Windows XP, which tries to allocate a contiguous chunk of retentiveness equally requested yesteryear -Xmx JVM parameters. Windows reserves some infinite for his ain together with seems besides allocate retentiveness unopen to one-half of retentiveness address bar, which consequently reduces contiguous retentiveness infinite somewhere less than 2GB, unopen to 1500 to 1600M together with when you lot laissez passer to a greater extent than than this size, JVM throws mistake as.

Could non create the Java virtual machine.
Invalid initial heap size: -Xms1.5G

Remember, this boundary on heap infinite is due to windows operating system's ain behavior. You tin laid maximum heap space, to a greater extent than than this size inward Linux or Solaris. Though maximum heap size for 32 flake or 64 flake JVM volition ever hold upward less than theoretical boundary of addressable memory. By the agency you lot tin larn this mistake due to many reasons, come across How to fix Invalid Initial together with Maximum heap size inward JVM for to a greater extent than details.

Why Linux or Solaris permit to a greater extent than maximum heap size than windows for same, 32 flake JVM?
This  point is besides related to second. Though in that place could hold upward multiple reasons for that merely I mean value It could hold upward because of Windows trying to allocate contiguous chunk of retentiveness equally Java heap space. Happy to hear your persuasion on this.


Can nosotros laid to a greater extent than than 4GB equally maximum heap size for 32 flake JVM running on 64 flake or x64 operating system?
This is a tricky question equally you lot are running 32 flake JVM on x64 server. In my persuasion you lot tin laid upto 4GB for 32 flake JVM merely non to a greater extent than than that. Though x64 Servers has to a greater extent than retentiveness for his needs together with since every procedure tin own got upto 2^64 flake it may hold off perfectly OK for 32 flake JVM to convey 4GB equally maximum heap size. In practice, I own got tried both Linux together with Solaris servers setting maximum heap size equally 4G merely it didn’t accept. Solaris goes to a greater extent than unopen to 4GB yesteryear allowing upto 3.6G (approx).


What is maximum heap size for 64 flake or x64 JVM, Is it 8GB or 16GB?
This query to a greater extent than often than non arise because of available physical retentiveness on machine. As no organization currently own got 2^64 flake of physical retentiveness or RAM together with often high halt servers has retentiveness unopen to 8G, 16GB or 32GB. Theoretical maximum retentiveness for x64 machines is 2^64 flake merely i time again its depend on how much your operating systems allows.I read some where that Windows allowed maximum of 32GB for 64 flake JVM.

Can I specify to a greater extent than than 1GB equally heap infinite if physical retentiveness is less than 1GB ?
Theoretically yes, because operating organization tin operate virtual retentiveness together with swap pages betwixt physical retentiveness together with virtual memory, when in that place is no room inward physical memory. Practically, if you lot are running on windows than it depends how far you lot tin go, I own got run Java plan amongst -Xmx1124M even though my machine has less than 1GB RAM.


That’s all on what is maximum Java heap infinite for 32 flake together with 64 flake JVM. As you lot come across maximum heap size depends upon host operating system. Solaris together with Linux provides to a greater extent than heap infinite than windows together with that could hold upward i of the many argue that Java Server application to a greater extent than often than non run on UNIX based systems. Let me know what’s your idea together with experience  on maximum Java heap infinite for  x86 together with x64 JVM running on both x86 together with x64 machines.

Further Learning
Java Memory Management
Difference betwixt JRE, JDK together with JVM
How to discovery if JVM is 32 or 64 flake inward Java
2 ways to solve java.lang.OutOfMemoryError inward Java
How ThreadLocal variable creates retentiveness leak inward Java spider web application
10 JVM options Java programmer should know

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