Parallel garbage collector

-xx:+useparallelgc

With this option, both the minor GC and the major GC use the parallel garbage collector

The thread used by the parallel garbage collector equals n when the host core n is less than or equal to 8 o'clock

N>8, a factor is multiplied by N to get the thread used by the collector

-xx:parallelgcthreads= Specifies the number of threads, when the parallel garbage collector uses multiple threads to make minor GC, it can cause fragmentation problems for the old age, and should be for different threads to open up different old age regions, thus moving old enough objects into older generations. Reduce the number of threads, increase the old age can, reduce fragmentation.

-xx:maxgcpausemillis= can specify pause time, virtual opportunity to make a series of adjustments, so as to meet this condition, may lead to throughput degradation

-xx:gctimeratio= the ratio between working time and GC time

-xmx the size of the specified heap

When the heap size is adjusted, by default, each increment is 20%, and the decrease is 5%. Parameters can be specified separately:

Growth:

-xx:yonggenerationsizeincrement=

-xx:tenuredgenerationsizeincrement=

Reduce:

-XX:AdaptiveSizeDecrementScaleFactor=<D>

Weak growth is x, then decrease equals x/d

-xms min memory

-XMX Max Memory

If more than 98% of the time is used to collect garbage, and less than 2% of the memory is recycled, then the outofmemory error is reported.

Parallel garbage collector