java - 线程转储 : How to see the condition of waiting/or any other condition?

Question

我对部署在生产环境中的应用程序进行了线程转储，该应用程序使用 logback。我不是分析线程转储的专家，但是，我必须这样做。正在学习，网上也看了一些文章。

下面是真正的线程转储:

"logback-8" #136 daemon prio=5 os_prio=0 tid=0x00007f3588001000 nid=0x13a waiting on condition [0x00007f35f8e7b000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x000000068d740338> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

"logback-7" #135 daemon prio=5 os_prio=0 tid=0x00007f356c030800 nid=0x139 waiting on condition [0x00007f35f8d7a000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x000000068d740338> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

"logback-6" #134 daemon prio=5 os_prio=0 tid=0x00007f357c018000 nid=0x138 waiting on condition [0x00007f3568ef0000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x000000068d740338> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

"logback-5" #133 daemon prio=5 os_prio=0 tid=0x00007f36b8003800 nid=0x137 waiting on condition [0x00007f35f9380000]
   java.lang.Thread.State: WAITING (parking)
        at sun.misc.Unsafe.park(Native Method)
        - parking to wait for  <0x000000068d740338> (a java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject)
        at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)
        at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.await(AbstractQueuedSynchronizer.java:2039)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:1088)
        at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:809)
        at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1067)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1127)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

正如我所见，这些线程中的大多数都处于 WAITING 状态。

但是我怎么知道他们到底在等什么？这些线程是否都在尝试“等待”“某事”？

我确实看了一些在线资料，但是当看到一个真正的线程转储时，如何采取步骤去理解，这些线程到底在做什么，在做什么，这对我来说没有任何意义他们在等待、阻塞等等。

谁能帮我理解一下？

Answer 1

据我分析线程转储，当您使用诸如 Spring 之类的框架或您在此处使用的其他库时 Logback。他们根据您的配置创建线程池。例如，您可以在 applicationcontext.xml 或任何基于 java 的配置类中找到此类配置。所以，它所做的是，它将在应用程序启动或第一次初始化调用时创建那么多线程。如果有任何任务到来，那么框架将从池中选择一个线程并分配它。任务完成后线程将返回池中，此时线程状态将类似于 WAITING (parking) 。这并不意味着它被任何线程阻塞。如果您的服务器有足够的能力处理这样的池，它不会导致任何性能问题。他们只是坐得很理想，因为他们没有任何任务要做。

您可以在 this 上找到更多信息如果您想查看线程转储的可视化分析方式，则可以使用 this .我发现这个网站很有帮助。只需上传您的转储文件。它会告诉该线程转储需要了解的所有内容。