Heap setup
 -Xms: initial heap size
 -Xmx: maximum heap size
 -20: Newsize = n: set younger generation size
 -20: Newratio = n: set the ratio of young generation to old generation. For example, if it is 3, it means that the ratio of the young generation to the old generation is 1:3, and the young generation accounts for 1 / 4 of the sum of the young generation and the old generation
 -20: Survivorratio = n: ratio of Eden region to two survivor regions in the younger generation. Note that there are two survivor areas. For example, 3 means Eden: Survivor=3:2, and one survivor area accounts for 1 / 5 of the whole young generation
 -20: Maxpermsize = n: set persistent generation size
 Collector settings
 -20: + useserialgc: set serial collector
 -20: + useparallelgc: set parallel collector
 -20: + useparalleledoldgc: set up parallel aging collector
 -20: + useconcmarksweepgc: set concurrent collector
 Garbage collection statistics
 -20: + printheatgc GC's heap details
 -20: + printgcdetails GC details
 -20: + printgctimestamps print GC time information
 -20: + printtenuringdistribution print age information, etc
 -20: + handlepromotionfailure old age distribution guarantee (true or false)
Parallel collector settings
 -20: Parallelgcthreads = n: sets the number of CPU s used by the parallel collector to collect. Number of parallel collection threads.
-20: Maxgcpausemillis = n: set the maximum pause time of parallel collection
 -20: Gctimeratio = n: set the percentage of garbage collection time in the running time of the program. The formula is 1/(1+n)
Concurrent collector settings
 -20: + cmsincrementalmode: set to incremental mode. It is suitable for single CPU.
-20: Parallelgcthreads = n: sets the number of CPU s used when the collection method of the younger generation of the concurrent collector is parallel collection. Number of parallel collection threads

• Give the thumbs-up
• Collection
• share
• • Article report