Increasing the JVM maximum heap size for memory intensive applications

Question

I need to run a Java memory intensive application that uses more than 2GB  but I am having problems to increase the heap maximum size  So far  I have tried the following approaches    Setting the -Xmx parameter  e g  -Xmx3000m  This approaches fails at the creation of the JVM  From what I ve googled  it looks like that -Xmx must be less than 2GB  Using the -XX  AggressiveHeap option  When I try this approach I get an  Not enough memory  error that tells that the heap size is 1273 4 MB  even though my computer has 8GB of memory    Is there another approach that I can try to increase the maximum heap size of the JVM  Here s a summary of the computer specs    OS  Windows 7  64 bit  Processor  Intel Core i7  2 66 GHz  Memory  8 GB java -version     java version  1 6 0 18  Java TM  SE Runtime Environment  build 1 6 0 18-b07  Java HotSpot TM  Client VM  build 16 0-b13  mixed mode  sharing

User · Answer

When you are using JVM in 32-bit mode  the maximum heap size that can be allocated is 1280 MB  So  if you want to go beyond that  you need to invoke JVM in 64-mode   You can use following     java -d64 -Xms512m -Xmx4g HelloWorld   where    -d64  Will enable 64-bit JVM -Xms512m  Will set initial heap size as 512 MB -Xmx4g  Will set maximum heap size as 4 GB   You can tune in -Xms and -Xmx as per you requirements  YMMV   A very good resource on JVM performance tuning  which might want to look into  http   java sun com javase technologies hotspot gc gc tuning 6 html

User · Answer

Get yourself a 64-bit JVM from Oracle

User · Answer

32-bit Java is limited to approximately 1 4 to 1 6 GB   Oracle 32 bit heap FAQ  Quote  The maximum theoretical heap limit for the 32-bit JVM is 4G  Due to various additional constraints such as available swap  kernel address space usage  memory fragmentation  and VM overhead  in practice the limit can be much lower  On most modern 32-bit Windows systems the maximum heap size will range from 1 4G to 1 6G  On 32-bit Solaris kernels the address space is limited to 2G  On 64-bit operating systems running the 32-bit VM  the max heap size can be higher  approaching 4G on many Solaris systems

User · Answer

I believe the 2GB limit is for 32-bit Java  I thought v1 6 was always 64 bit  but try forcing 64 bit mode just to see  add the -d64 option

User · Answer

In my case  -Xms1024M -Xmx1024M is work -Xms1024M -Xmx2048M result  Could not reserve enough space for object heap after use JVM 64 bit  it allows using 2GB RAM  because I am using win server 2012 please see the available max heap size for JVM 32 bit on several OSs  https   www codementor io  suryab does-32-bit-or-64-bit-jvm-matter-anymore-w0sa2rk6z

User · Answer

Below conf works for me   JAVA HOME  JDK1 7 51-64 jdk1 7 0 51  PATH  JDK1 7 51-64 jdk1 7 0 51 bin  PATH export PATH export JAVA HOME  JVM ARGS  -d64 -Xms1024m -Xmx15360m -server    JDK1 7 51-64 jdk1 7 0 51 bin java  JVM ARGS -jar  dirname  0  ApacheJMeter jar

[java] Increasing the JVM maximum heap size for memory intensive applications

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