By default, JVM does not specify a way to perform a full garbage collection by a user request. You may know about java.lang.System.gc(), but then you must already know that this function only suggests to the JVM to run garbage collection.

Fortunately there is ForceGarbageCollection() defined in JVM Tool Interface (JVMTI) spec. And that's what this library here is all about.

Building

You can just grab precompiled binaries from out/ in this repo.

But building everything by yourself is easy, too.
Open your shell and cd into this repo directory.

Java

javac -source 1.5 -target 1.5 src/jvmforcegcagent/main/java/name/ltp/jvmforcegcagent/JvmForceGcAgent.java && cd src/jvmforcegcagent/main/java && jar cvf ../../../../out/jvmforcegcagent.jar name/ltp/jvmforcegcagent/JvmForceGcAgent.class && rm name/ltp/jvmforcegcagent/JvmForceGcAgent.class && cd ../../../../

Windows x86

gcc -shared -Wall -D_JNI_IMPLEMENTATION_ -Wl,--kill-at -I"%JAVA_HOME%/include" -I"%JAVA_HOME%/include/win32"^
 -o out/jvmforcegcagent-win32.dll^
 src/jvmforcegcagent/main/native/jvmforcegcagent.c^
 && strip out/jvmforcegcagent-win32.dll

Windows x86-64

gcc -shared -Wall -D_JNI_IMPLEMENTATION_ -Wl,--kill-at -I"%JAVA_HOME%/include" -I"%JAVA_HOME%/include/win32"^
 -o out/jvmforcegcagent-win64.dll^
 src/jvmforcegcagent/main/native/jvmforcegcagent.c^
 && strip out/jvmforcegcagent-win64.dll

Linux x86-64

cc -shared -Wall -fpic -I$JAVA_HOME/include/ -I$JAVA_HOME/include/linux/ \
 -o out/libjvmforcegcagent-tux64.so \
 src/jvmforcegcagent/main/native/jvmforcegcagent.c \
 && strip out/libjvmforcegcagent-tux64.so

Running

Windows x86

 java -agentpath:jvmforcegcagent/out/jvmforcegcagent-win32.dll -Djava.library.path=jvmforcegcagent/out/ -cp jvmforcegcagent/out/* com.example.YourApp

Windows x86-64

 java -agentpath:jvmforcegcagent/out/jvmforcegcagent-win64.dll -Djava.library.path=jvmforcegcagent/out/ -cp jvmforcegcagent/out/* com.example.YourApp

Linux x86-64

 java -agentpath:jvmforcegcagent/out/libjvmforcegcagent-tux64.so -Djava.library.path=jvmforcegcagent/out/ -cp jvmforcegcagent/out/* com.example.YourApp

Usage

if(name.ltp.jvmforcegcagent.JvmForceGcAgent.i() != null)
	name.ltp.jvmforcegcagent.JvmForceGcAgent.i().forceGc();

License

Licensed under the CC0 1.0: http://creativecommons.org/publicdomain/zero/1.0/