java threadump意义"等待条件"

Question

我有一个应用程序的threaddump,显示3个线程如下.

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"http-443-11" daemon prio=10 tid=0x00000000473bc800 nid=0x3590 waiting on condition [0x0000000061818000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000007612a3880> (a java.util.concurrent.Semaphore$NonfairSync)

"http-443-4" daemon prio=10 tid=0x00000000451f6000 nid=0x243a waiting on condition [0x0000000055354000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000007612a3880> (a java.util.concurrent.Semaphore$NonfairSync)

"http-443-7" daemon prio=10 tid=0x000000004602e000 nid=0x2974 waiting on condition [0x000000005e6e7000]
   java.lang.Thread.State: WAITING (parking)
    at sun.misc.Unsafe.park(Native Method)
    - parking to wait for  <0x00000007612a3880> (a java.util.concurrent.Semaphore$NonfairSync)

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"等待条件[]"有什么意义？[]中的数字有什么意义？

Answer 1

在线程堆栈中我们可以看到线程是守护线程，正在等待任务到来。由于这些线程是在 JVM 启动时创建的，因此除非 JVM 退出或任何非守护线程未运行，否则它们不会被杀死，因此它们等待任务到来。假设垃圾收集线程是一个守护线程，它可能不会一直运行，它可能处于等待状态。