OOM分析 gc overhead limit exceeded

今天生产环境出现Java.lang.OutOfMemoryErrot: GC overhead limit exceeded

网上查了资料这个错只有在java.lang.OutOfMemoryError: GC overhead limit exceeded（某项操作使用大量内存时发生）

资料：http://blog.csdn.net/jiandanjinxin/article/details/51740890

好吧，那只能先heapdump下看看到底哪个没有回收

方案一：

重启前先把修改一下tomcat的启动参数，万一再发生OOM可以自动dump堆栈信息。

1、在tomcat启动参数中加入两个参数 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/export/home/tomcat/domains/server2/oom.hprof

2、重启tomcat

参数说明

（1）-XX:+HeapDumpOnOutOfMemoryError 表示当JVM发生OOM时，自动生成DUMP文件。

（2）-XX:HeapDumpPath=存储文件/目录表示生成DUMP文件的路径

方案二：

生产系统，总不能等着他当吧，既然是OOM那就先看下生产上的堆内存分配情况

jmap -heap PID

Debugger attached successfully.

Server compiler detected.

JVM version is 25.112-b15

using thread-local object allocation.

Parallel GC with 4 thread(s)

Heap Configuration:

MinHeapFreeRatio = 0

MaxHeapFreeRatio = 100

MaxHeapSize = 2063597568 (1968.0MB)

NewSize = 42991616 (41.0MB)

MaxNewSize = 687865856 (656.0MB)

OldSize = 87031808 (83.0MB)

NewRatio = 2

SurvivorRatio = 8

MetaspaceSize = 21807104 (20.796875MB)

CompressedClassSpaceSize = 1073741824 (1024.0MB)

MaxMetaspaceSize = 17592186044415 MB

G1HeapRegionSize = 0 (0.0MB)

Heap Usage:

PS Young Generation

Eden Space:

capacity = 161480704 (154.0MB)

used = 161480704 (154.0MB)

free = 0 (0.0MB)

100.0% used

From Space:

capacity = 229113856 (218.5MB)

used = 82645888 (78.8172607421875MB)

free = 146467968 (139.6827392578125MB)

36.07197287971968% used

To Space:

capacity = 229113856 (218.5MB)

used = 0 (0.0MB)

free = 229113856 (218.5MB)

0.0% used

PS Old Generation

capacity = 1375731712 (1312.0MB)

used = 1375583088 (1311.8582611083984MB)

free = 148624 (0.1417388916015625MB)

99.98919673082305% used

23110 interned Strings occupying 2726400 bytes.