-Xms20m Java堆初始容量
-Xmx20m Java堆最大容量
-Xmn10m Java堆年轻代大小
-XX:+PrintGCDetails 打印GC信息
-XX:+PrintGCDateStamps 打印GC时间
-XX:SurvivorRatio=8 n:年轻代中Eden区与两个Survivor区的比值。注意Survivor区有两个。如8，表示Eden：Survivor=8：2，一个Survivor区占整个年轻代的1/10
-XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=D:/logs
2017-12-16T12:01:33.138+0800: [GC (Allocation Failure) [PSYoungGen: 7565K->996K(9216K)] 7565K->3945K(19456K), 0.0035977 secs] [Times: user=0.00 sys=0.00, real=0.00 secs]
2017-12-16T12:01:33.145+0800: [GC (Allocation Failure) [PSYoungGen: 9188K->1002K(9216K)] 12137K->9606K(19456K), 0.0075101 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
2017-12-16T12:01:33.153+0800: [Full GC (Ergonomics) [PSYoungGen: 1002K->0K(9216K)] [ParOldGen: 8604K->9512K(10240K)] 9606K->9512K(19456K), [Metaspace: 3491K->3491K(1056768K)], 0.1132212 secs] [Times: user=0.25 sys=0.00, real=0.11 secs]
2017-12-16T12:01:33.267+0800: [Full GC (Ergonomics) [PSYoungGen: 7191K->6654K(9216K)] [ParOldGen: 9512K->7974K(10240K)] 16704K->14628K(19456K), [Metaspace: 3493K->3493K(1056768K)], 0.1067505 secs] [Times: user=0.36 sys=0.00, real=0.11 secs]
2017-12-16T12:01:33.374+0800: [Full GC (Allocation Failure) [PSYoungGen: 6654K->6654K(9216K)] [ParOldGen: 7974K->7956K(10240K)] 14628K->14610K(19456K), [Metaspace: 3493K->3493K(1056768K)], 0.0712906 secs] [Times: user=0.45 sys=0.00, real=0.07 secs]
PSYoungGen(新生代): Parallel Scavenge收集器
ParOldGen(老年代)： Parallel Old收集器