1. 检查程序是否有问题。 是不是写死循环不停地创建并持有对象导致内存不足

1. 内存确实不够， 分为老年代内存不足和永久代内存不足

看一段 GC 日志：在 Full GC 结束后， 可是老年代占用空间还是接近或者等于老年代最大空间， 说明老年代空间确实分配不够。 调大 -Xms、 -Xmx 并保持新生代大小不变。直到 GC 日志不出现keyword Exception in thread  “main” java.lang.OutOfMemoryError: Java heap space。

2016-01-19T14:18:19.883+0800: 179.163: [CMS-concurrent-reset-start]

2016-01-19T14:18:19.893+0800: 179.173: [CMS-concurrent-reset: 0.009/0.009 secs] [Times: user=0.02 sys=0.00, real=0.01 secs]

{Heap before GC invocations=154 (full 1):

 par new generation   total 943744K, used 850746K [0x0000000757000000, 0x0000000797000000, 0x0000000797000000)

  eden space 838912K, 100% used [0x0000000757000000, 0x000000078a340000, 0x000000078a340000)

  from space 104832K,  11% used [0x000000078a340000, 0x000000078aecea30, 0x00000007909a0000)

  to   space 104832K,   0% used [0x00000007909a0000, 0x00000007909a0000, 0x0000000797000000)

 concurrent mark-sweep generation total 1560576K, used 1560576K [0x0000000797000000, 0x00000007f6400000, 0x00000007f6400000)

 concurrent-mark-sweep perm gen total 159744K, used 69030K [0x00000007f6400000, 0x0000000800000000, 0x0000000800000000)

2016-01-19T14:18:19.883+0800: 179.163: [CMS-concurrent-reset-start]

2016-01-19T14:18:19.893+0800: 179.173: [CMS-concurrent-reset: 0.009/0.009 secs] [Times: user=0.02 sys=0.00, real=0.01 secs]

{Heap before GC invocations=154 (full 1):

 par new generation   total 943744K, used 850746K [0x0000000757000000, 0x0000000797000000, 0x0000000797000000)

  eden space 838912K, 100% used [0x0000000757000000, 0x000000078a340000, 0x000000078a340000)

  from space 104832K,  11% used [0x000000078a340000, 0x000000078aecea30, 0x00000007909a0000)

  to   space 104832K,   0% used [0x00000007909a0000, 0x00000007909a0000, 0x0000000797000000)

 concurrent mark-sweep generation total 1560576K, used 345246K [0x0000000797000000, 0x00000007f6400000, 0x00000007f6400000)

 concurrent-mark-sweep perm gen total 159744K, used 159744K [0x00000007f6400000, 0x0000000800000000, 0x0000000800000000)