在分析 Java 应用程序时,我注意到一个有趣的事实。当 JVM 处于 GC 时,死亡线程转储的螺旋如下所示:
"1304802943@qtp-393978767-9985" prio=10 tid=0x00007f3ed02dd000 nid=0x74e7 in Object.wait() [0x000000004febb000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:626)
- locked <0x00000007aed40048> (a org.mortbay.thread.QueuedThreadPool$PoolThread)
"26774405@qtp-393978767-9984" prio=10 tid=0x00007f3ee4b37000 nid=0x74e6 in Object.wait() [0x0000000045d1a000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:626)
- locked <0x00000007aed83aa0> (a org.mortbay.thread.QueuedThreadPool$PoolThread)
"764808089@qtp-393978767-9983" prio=10 tid=0x00007f3ee4c50000 nid=0x74e5 in Object.wait() [0x000000004ad6a000]
java.lang.Thread.State: TIMED_WAITING (on object monitor)
at java.lang.Object.wait(Native Method)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:626)
- locked <0x00000007aed5c448> (a org.mortbay.thread.QueuedThreadPool$PoolThread)
因此,状态中有很多线程TIMED_WAITING
。从理论上讲,这种情况很容易在正常运行的应用程序中找到(应用程序目前根本没有任何传入请求),但我什至找不到单个请求调度线程做有用的事情(标称命中率约为 100 hps)。
这种行为与 GC 有什么关系,还是只是巧合?