JVM parameter interpretation

JVM Common parameters in

 

Xms Starting memory

Xmx Maximum memory

Xmn New generation memory

Xss Stack size . After the thread is created , The amount of memory allocated to each thread

-XX:NewRatio=n: Set the ratio of young generation to old generation . Such as : by 3, The ratio of young generation to old generation is 1：3, The younger generation makes up the younger generation and the older generation 1/4

-XX:SurvivorRatio=n: Young generation Eden District and two Survivor Area ratio . Be careful Survivor There are two. . Such as ：3, Express Eden：Survivor=3：2, One Survivor District accounts for the whole young generation 1/5

-XX:MaxPermSize=n: Set persistent generation size

Collector settings
-XX:+UseSerialGC: Set up a serial collector
-XX:+UseParallelGC: Set up parallel collectors
-XX:+UseParalledlOldGC: Set up parallel older collector
-XX:+UseConcMarkSweepGC: Set up concurrent collectors
Garbage collection statistics
-XX:+PrintGC
-XX:+PrintGCDetails
-XX:+PrintGCTimeStamps
-Xloggc:filename
Parallel collector settings
-XX:ParallelGCThreads=n: Set the... Used by the parallel collector collection CPU Count . Number of parallel collection threads .
-XX:MaxGCPauseMillis=n: Set the maximum pause time for parallel collection
-XX:GCTimeRatio=n: Set the percentage of garbage collection time in the running time of the program . Formula for 1/(1+n)
Concurrent collector settings
-XX:+CMSIncrementalMode: Set to incremental mode . Applicable to single CPU situation .
-XX:ParallelGCThreads=n: When setting the collection mode of the younger generation of the concurrent collector to parallel collection , The use of CPU Count . Number of parallel collection threads .