Java JVM & Garbage Collection Type
- JVM Options Info
java -XX:+PrintCommandLineFlags -version
jeonguk@JEONGUKui-MacBook-Pro ~ java -XX:+PrintCommandLineFlags -version
-XX:InitialHeapSize=268435456 -XX:MaxHeapSize=4294967296 -XX:+PrintCommandLineFlags -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
java version "1.8.0_151"
Java(TM) SE Runtime Environment (build 1.8.0_151-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.151-b12, mixed mode)
jeonguk@JEONGUKui-MacBook-Pro ~
- Available Options by GC Type.
Serial GC :
-XX:+UseSerialGC
Parallel GC :
-XX:+UseParallelGC
-XX:ParallelGCThreads=value
Parallel Compacting GC :
-XX:+UseParallelOldGC
CMS GC :
-XX:+UseConcMarkSweepGC
-XX:+UseParNewGC
-XX:+CMSParallelRemarkEnabled
-XX:CMSInitiatingOccupancyFraction=value
-XX:+UseCMSInitiatingOccupancyOnly
G1 (In JDK 6, these two options must be used together.)
-XX:+UnlockExperimentalVMOptions
-XX:+UseG1GC
- Minor GC
- Collecting garbage from Young space (consisting of Eden and Survivor spaces) is called a Minor GC.
- Major GC
- cleaning the Tenured space.
- Full GC
- cleaning the entire Heap – both Young and Tenured spaces.
ps ef | grep java
jstat -gc -t <java process ID> 1s
jstat Reference
- https://docs.oracle.com/javase/8/docs/technotes/tools/unix/jstat.html