how to increase java heap memory permanently

Question

I have one problem with java heap memory  I developed one client server application in java which is run as a windows service it requires more than 512MB of memory  I have 2GB of RAM but when I run my application it throws an exception     Out of memory error java heap space   but I have already set heap size  maximum  512MB  in the java control panel and I still get the same error  I can t set heap size through the command line because my application runs as a windows service so how can I increase the default heap size

User · Answer

You also use this below to expand the memory

export _JAVA_OPTIONS="-Xms512m -Xmx1024m -Xss512m -XX:MaxPermSize=1024m"

Xmx specifies the maximum memory allocation pool for a Java virtual machine (JVM)

Xms specifies the initial memory allocation pool.

Xss setting memory size of thread stack

XX:MaxPermSize: the maximum permanent generation size

User · Answer

if you need to increase reserved memory  there are VM parameters -Xms and -Xmx  usage e g  -Xms512m -Xmx512m   There is also parameter -XX MaxPermSize 256m which changes memory reserved for permanent generationIf your application runs as windows service  in Control panels -  Administration tools -  Services you can add some run parameters to your service

User · Answer

The Java Virtual Machine takes two command line arguments which set the initial and maximum heap sizes  -Xms and -Xmx  You can add a system environment variable named  JAVA OPTIONS  and set the heap size values there  For example if you want a 512Mb initial and 1024Mb maximum heap size you could use   under Windows   SET  JAVA OPTIONS   -Xms512m -Xmx1024m   under Linux   export  JAVA OPTIONS  -Xms512m -Xmx1024m    It is possible to read the default JVM heap size programmatically by using totalMemory   method of Runtime class  Use following code to read JVM heap size   public class GetHeapSize       public static void main String  args              Get the jvm heap size          long heapSize   Runtime getRuntime   totalMemory               Print the jvm heap size          System out println  Heap Size       heapSize

User · Answer

Please note that increasing the Java heap size following an java lang OutOfMemoryError  Java heap space is quite often just a short term solution    This means that even if you increase the default Java heap size from 512 MB to let s say 2048 MB  you may still get this error at some point if you are dealing with a memory leak  The main question to ask is why are you getting this OOM error at the first place  Is it really a Xmx value too low or just a symptom of another problem   When developing a Java application  it is always crucial to understand its static and dynamic memory footprint requirement early on  this will help prevent complex OOM problems later on  Proper sizing of JVM Xms  amp  Xmx settings can be achieved via proper application profiling and load testing

User · Answer

This worked for me   export  JAVA OPTIONS  -Xmx1g   It s important that you have no spaces because for me it did not work  I would suggest just copying and pasting  Then I ran   java -XshowSettings vm   and it will tell you   Picked up  JAVA OPTIONS  -Xmx1g

[java] how to increase java heap memory permanently?

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