FULL GC有可能导致JVM暂停1分钟以上吗?

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qianhd 2011-12-30

与另外个程序交互有个心跳检测, 15s/次, 31s没有收到心跳检测的返回消息就认为连接断了,

现在遇到一个诡异问题, 不知什么原因导致程序中1分多钟内日志无任何输出, 接着就是检测到超时, 可是接着连续输出多次发送keepalive.

发送keepalive就是很简单的java.util.Timer, 速率固定

启动参数
-Xms16m -Xmx128m -XX:+HeapDumpOnOutOfMemoryError

程序启动时间[15:55:10.225] [23.12.2011]

第一次

[09:51:16.288] [26.12.2011] [Thread-14][DEBUG] Keepalive receiver started or reseted.

[09:53:26.819] [26.12.2011] [Timer-9197][ERROR] Keepalive timeout reached

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent

[09:53:26.819] [26.12.2011] [Timer-9][DEBUG] Keepalive sent      

[09:53:26.819] [26.12.2011] [Timer-9197][DEBUG] Sent <Disconnect/>

重连启动后第二次

[09:57:17.053] [26.12.2011] [Thread-9207][DEBUG] Keepalive receiver started or reseted.

[09:58:29.381] [26.12.2011] [Timer-9259][ERROR] Keepalive timeout reached

[09:58:29.381] [26.12.2011] [Timer-9259][DEBUG] Sent <Disconnect/>

[09:58:29.397] [26.12.2011] [Timer-9200][DEBUG] Keepalive sent

[09:58:29.397] [26.12.2011] [Timer-9200][DEBUG] Keepalive sent

[09:58:29.397] [26.12.2011] [Timer-9200][DEBUG] Keepalive sent

[09:58:29.397] [26.12.2011] [Timer-9200][DEBUG] Keepalive sent

qianhd 2011-12-30

另外 -Xloggc 这个jvm的gc日志能以压缩的形式输出吗? 或者过滤一些.

RednaxelaFX 2011-12-30

GC暂停超过1分钟的情况不是没有，但以-Xmx128m的配置来看这个很诡异。
请问能使用 -XX:+PrintSafepointStatistics 来看看VM暂停的统计信息么？
一共是这几个参数：

  product(bool, PrintSafepointStatistics, false,                            \
          "print statistics about safepoint synchronization")               \
                                                                            \
  product(intx, PrintSafepointStatisticsCount, 300,                         \
          "total number of safepoint statistics collected "                 \
          "before printing them out")                                       \
                                                                            \
  product(intx, PrintSafepointStatisticsTimeout,  -1,                       \
          "print safepoint statistics only when safepoint takes"            \
          " more than PrintSafepointSatisticsTimeout in millis")            \

qianhd 2011-12-30

应该可以
但是这问题也就遇到过这一次未必能重现
这地方只要出现过一次的问题都能报bug

就连temp目录垃圾文件太多导致程序里创建临时文件太慢使得程序响应变慢都能报个bug.