1.JVM (Java Virtual machine)
1.-xms Initial Heap Size2.-xmx Maximum Heap Size3.-XMN Youth Generation Size4.-XSS the stack size per thread5.-XX:+USEPARNEWGC Youth GenerationThe garbage collection method isParallel collection 6.-xx:+useparalleloldgcOld age garbage Collection method for parallel collection
7.-xx:parallelgcthreads the number of threads in the parallel collector (preferably equal to the number of processors)8.-xx:maxgcpausemillis maximum time per youth garbage collection (max. Pause time)9.-xx:+useadaptivesizepolicy automatic selection of the size of the youth and corresponding survivor area ratio10.-xx:gctimeratio set garbage collection time as a percentage of program run time11.-XX:+SCAVENGEBEFOREFULLGC full GC before calling YGC
21.-xx:newsize Youth Generation size (for 1.3/1.4)22.-xx:maxnewsize Youth Generation Max (for 1.3/1.4)23.-xx:permsize Set the persistent generation (Perm Gen) initial value24.-xx:maxpermsize maximum value for persistent generations
2.CMS (Concurrent mark-sweep)
A garbage collector at the expense of throughput to obtain the shortest recovery pause time. This garbage collector is ideal for applications that require a server response speed. After starting the JVM parameter plus -XX:+USECONCMARKSWEEPGC , this parameter indicates that the recycle of the old age uses CMS. The basic algorithm used by the CMS is: Mark-erase.
1.-XX:+USECONCMARKSWEEPGC using CMS Memory collection
2.-xx:cmsfullgcsbeforecompaction How many times after the memory compression3.-xx:+cmsparallelremarkenabled Decrease Mark Pause4.-xx+usecmscompactatfullcollection in full GC, the compression of older generations5.-xx:+usecmsinitiatingoccupancyonly starting a CMS collection using a manual definition of the initialization definition6.-xx:cmsinitiatingoccupancyfraction=70 use CMS as garbage collection, use 70% after starting CMS collect7.-xx:cmsinitiatingpermoccupancyfraction setting Perm Gen usage to reach how much ratio is triggered8.-xx:+cmsincrementalmode set to incremental mode
Java Advanced (iii) JVM parameter description
