cpu高 thread vm_GC task thread#0 (ParallelGC) 占用cpu过高

最近在查线上应用cpu过高时遇到一个问题，根据线程号追踪发现是gc线程占用大量的cpu。

top -p 7794

top - 15:31:22 up 883 days, 35 min, 1 user, load average: 0.23, 0.37, 0.72

Tasks: 21 total, 0 running, 21 sleeping, 0 stopped, 0 zombie

Cpu(s): 2.1%us, 0.2%sy, 0.0%ni, 95.2%id, 2.4%wa, 0.0%hi, 0.1%si, 0.0%st

Mem: 32955440k total, 29792780k used, 3162660k free, 838724k buffers

Swap: 16779884k total, 147720k used, 16632164k free, 9962112k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

7815 admin 15 0 7424m 4.7g 9.9m S 1524.4 15.0 0:45.76 java

7794 admin 18 0 7424m 4.7g 9.9m S 0.0 15.0 0:00.00 java

7796 admin 15 0 7424m 4.7g 9.9m S 0.0 15.0 0:05.73 java

7797 admin 16 0 7424m 4.7g 9.9m S 0.0 15.0 2:50.67 java

7798 admin 16 0 7424m 4.7g 9.9m S 0.0 15.0 2:50.52 java

7799 admin 16 0 7424m 4.7g 9.9m S 0.0 15.0 2:51.82 java

7800 admin 16 0 7424m 4.7g 9.9m