Maximum heap size using for Java process in Windows 10 64 bit running 64 bit JVM

java jvm 64-bit windows-10 heap-size
Brother picture Brother · Apr 7, 2017 · Viewed 22.4k times · Source

What is maximum Heap size for Java process running on Windows 10 64 bits, with 64 bits JVM? My machine has 8 GB of RAM. And I am running Java 8. I trying to run BFS on huge graph for experimental purposes. While running BFS I am monitoring Heap size being used in Java Visual VM. According to Visual VM heap utilization is always less than 2000 MB regardless of providing following JVM parameters

-Xms2048m
-Xmx3072m
-XX:ReservedCodeCacheSize=240m
-XX:+UseConcMarkSweepGC
-XX:SoftRefLRUPolicyMSPerMB=50
-ea
-Dsun.io.useCanonCaches=false
-Djava.net.preferIPv4Stack=true
-XX:+HeapDumpOnOutOfMemoryError
-XX:-OmitStackTraceInFastThrow

I did some research over internet but could not find any specific answer related to the system specification I am using. Can a java process use more than 2 GB on Windows 10 64 bit and 64 bit JVM? As Guidelines for Java Heap sizing the limit for Windows XP/2008/7 is 2 GB.

Answer

Kayaman picture Kayaman · Apr 7, 2017

On a 64-bit machine, with 64-bit JVM you can work with multi gigabyte heaps (dozens and dozens of GBs). I'm not sure it's limited in any way except by the available memory (and the theoretical address space of a 64-bit pointer).

Of course if you're working with a huge heap, the GC has a lot more work to do and you may find that you need to scale horizontally instead of vertically, to maintain a good performance.

If VisualVM isn't showing you using more than 2GB (the initial heap size given with -Xms), then it probably just doesn't need more than that. You've given the permission to use up to 3GB (-Xmx), but the JVM won't allocate more memory just for the fun of it.

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