What is the memory footprint of the JVM and how can I minimize it?

java memory jvm memory-footprint
Martin Kersten picture Martin Kersten · Jul 24, 2016 · Viewed 13.2k times · Source

I just wanted to know what the actual footprint of the JavaVM (Sun, Linux) is when one starts to start to spawn multiple processes of JVMs. When I remember well those should share the rt.jar (and maybe beyond?). Does those JVM share the JIT cache (all JVM feature the same Classpath)?

Is there anything I can do to reduce the overhead of multi-instance JVM? (beside of setting smaller limits for the heap)?

Anything I can do while programming the application?

Can I share memory areas? Maybe share mapped memory blocks?

Answer

apangin picture apangin · Jul 24, 2016

This post describes what makes up a Java application footprint. That is, if you want to reduce footprint, you need to reduce those parts: Java Heap, Metaspace, Code Cache, direct buffers, number of threads etc.

Instances of HotSpot JVM do not communicate to each other for sharing data. Basically they share nothing except for the things shared by the OS, i.e. the dynamic libraries (.so) and read-only memory-mapped files (.jars).

It's up to the application to provide further sharing via IPC mechanisms, e.g. memory-mapped files.

Related questions

Java Refuses to Start - Could not reserve enough space for object heap

Background We have a pool of aproximately 20 linux blades. Some are running Suse, some are running Redhat. ALL share NAS space which contains the following 3 folders: /NAS/app/java - a symlink that points to an installation of a Java …

Read More
Increase heap size in java for weka

I'm trying to increase the heap size in java for weka which keeps crashing. I used the suggested line: > java -Xmx500m -classpath but I get the following error: -classpath requires class path specification I'm not sure what this …

Read More
What does the UseCompressedOops JVM flag do and when should I use it?

What does the HotSpot JVM flag -XX:+UseCompressedOops do and when should I use it? What sort of performance and memory-usage differences will I see when using it on a 64-bit Java instance (vs. not using it)?

Read More