**Full GC:cleaning the entire Heap – both Young and Tenured spaces.**
日志s：
2016-10-12T13:23:48.918+0800: 2.599: [Full GC (System.gc()) 2016-10-12T13:23:48.918+0800: 2.599: [CMS: 0K->28110K(15728640K), 0.2457050 secs] 3303107K->28110K(20316160K), [Metaspace: 18520K->18520K(1067008K)], 0.2534340 secs] [Times: user=0.43 sys=0.08, real=0.26 secs]
1、system.gc一般是代码调用
concurrent mark-sweep generation total 15728640K, used 15728640K
1、cms full gc一点没释放？jmap分析是否内存泄漏
Refer：
https://plumbr.eu/blog/garbage-collection/minor-gc-vs-major-gc-vs-full-gc
