@tonniky 主要是通过 jstat -gc 命令观察 fgc 太频繁,最终还是通过 MAT 找到出现内存泄露了. 这个日志 ParOldGen 在 FGC 前后基本上没有变化, 表示内存被某个东西占用了,没法释放.

@Jooooooooo 问题解决了,谢谢你, 用 MAT 分析后发现问题了.

@Jooooooooo GC log 能看出什么原因吗

gc log 如下所示:

```
[Full GC (Ergonomics) 3881881K->2889968K(4038144K), 4.5727780 secs]
[Full GC (Ergonomics) 3881681K->2889026K(4038144K), 3.0774469 secs]
[Full GC (Ergonomics) 3881614K->2888641K(4038144K), 2.2580244 secs]
[Full GC (Ergonomics) 3881614K->2887646K(4038144K), 4.2011123 secs]
17:46:48,926
[Full GC (Ergonomics) 3881614K->2887135K(4038144K), 2.7401695 secs]
[Full GC (Ergonomics) 3881612K->2886768K(4038144K), 4.0454051 secs]
[Full GC (Ergonomics) 3881612K->2887188K(4038144K), 2.3936678 secs]
[Full GC (Ergonomics) 3881608K->2887642K(4038144K), 4.0567923 secs]
[Full GC (Ergonomics) 3881918K->2886507K(4038144K), 4.6593080 secs]
[Full GC (Ergonomics) 3881783K->2886918K(4038144K), 4.0624945 secs]
17:47:38,528
[Full GC (Ergonomics) 3881782K->2865376K(4038144K), 0.8624403 secs]
[Full GC (Ergonomics) 3881694K->2865692K(4038144K), 2.9422862 secs]
[Full GC (Ergonomics) [PSYoungGen: 1085440K->69778K(1241600K)] [ParOldGen: 2796159K->2796144K(2796544K)] 3881599K->2865922K(4038144K), [Metaspace: 238529K->238529K(1271808K)], 3.3878363 secs] [Times: user=71.81 sys=0.39, real=3.39 secs]
[Full GC (Ergonomics) [PSYoungGen: 1085440K->71060K(1241600K)] [ParOldGen: 2796144K->2796064K(2796544K)] 3881584K->2867125K(4038144K), [Metaspace: 238529K->238529K(1271808K)], 4.3924844 secs] [Times: user=93.60 sys=0.58, real=4.40 secs]
17:48:10,361
17:48:13,784
17:48:13,831
[Full GC (Ergonomics) [PSYoungGen: 1085440K->78286K(1241600K)] [ParOldGen: 2796064K->2795878K(2796544K)] 3881504K->2874164K(4038144K), [Metaspace: 238529K->238529K(1271808K)], 4.7109424 secs] [Times: user=101.27 sys=0.58, real=4.71 secs]
[Full GC (Ergonomics) [PSYoungGen: 1085440K->83326K(1241600K)] [ParOldGen: 2795878K->2795708K(2796544K)] 3881318K->2879035K(4038144K), [Metaspace: 238529K->238529K(1271808K)], 4.0158977 secs] [Times: user=85.44 sys=0.50, real=4.01 secs]
[Full GC (Ergonomics) [PSYoungGen: 1085440K->82672K(1241600K)] [ParOldGen: 2795708K->2795707K(2796544K)] 3881148K->2878379K(4038144K), [Metaspace: 238529K->238529K(1271808K)], 4.2606693 secs] [Times: user=90.71 sys=0.57, real=4.26 secs]
17:48:31,473
[Full GC (Ergonomics) [PSYoungGen: 1085440K->110615K(1241600K)] [ParOldGen: 2795707K->2795655K(2796544K)] 3881147K->2906270K(4038144K), [Metaspace: 238529K->238529K(1271808K)], 4.5355769 secs] [Times: user=96.77 sys=0.61, real=4.54 secs]

```