分析java堆栈跟踪，哪些线程正在运行

发布于 2024-10-29 07:57:58 字数 459 浏览 3 评论 0原文

我正在分析 java 中的堆栈跟踪转储，但不知道如何判断哪些线程正在实际运行。在我看来，线程要么正在运行，要么正在等待锁，要么正在休眠，要么等待被调度。

在我的堆栈跟踪中，我看到以下状态

java.lang.Thread.State: WAITING (on object monitor)
java.lang.Thread.State: RUNNABLE
java.lang.Thread.State: TIMED_WAITING (sleeping)
java.lang.Thread.State: WAITING (parking)
java.lang.Thread.State: TIMED_WAITING (parking)

首先，这些状态到底意味着什么？

其次，我有 11 个可运行的线程，其中两个正在等待某个条件。这是否意味着 9 个线程同时运行？这似乎不可能，因为我的机器没有那么多核心。

原文

I'm analyzing stack trace dumps in java and don't know how I can tell which threads are actually running. The way I see it a thread is either running, waiting on a lock, sleeping or waiting to be scheduled.

In my stack trace I see the following states

java.lang.Thread.State: WAITING (on object monitor)
java.lang.Thread.State: RUNNABLE
java.lang.Thread.State: TIMED_WAITING (sleeping)
java.lang.Thread.State: WAITING (parking)
java.lang.Thread.State: TIMED_WAITING (parking)

First, what exactly do these states mean?

Second, I have 11 threads that are runnable, two of which are waiting on a condition. Does that mean 9 threads are running simultaneously? It doesn't seem possible since my machine doesn't have that amount of cores.

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谁人与我共长歌 2024-11-05 07:57:58

术语“可运行”可能并不意味着“当前正在运行”，而是“处于运行状态”。您所回避的差异是，在任何给定时间可以运行的最大线程数等于您的核心数。

要更详细地理解它，您需要知道其他两个的含义。 WAITING 意味着线程已在某个对象上挂起。

while(<condition holds>)
    obj.wait()

在这里，当前线程当前正在 obj 的监视器上WAITING。这将迫使该线程挂起，操作系统可以在其中调度另一个线程运行。

TIMED_WAITING 只是将线程挂起一段时间。

因此，如果线程没有等待或睡眠，它就会被视为运行。

从文档中获得更多见解。

可运行线程的线程状态。一个
处于可运行状态的线程是
在Java虚拟机中执行
但它可能正在等待其他
来自操作系统的资源
例如处理器。

我认为最后一部分就是您正在寻找的内容。从物理上讲，操作系统并行运行的线程数量不能多于内核数量。
所有 9 个线程都可以同时运行，但只有 n 会并行运行（n 是核心数量）。

Condition.await 也是如此

编辑：

对不起，丰富 - 应该链接我的资源 http://download.oracle.com/javase/1.5.0/docs/api/java/lang/Thread.State.html#RUNNABLE

The term Runnable may not mean 'currently running' but rather 'is in a state of running'. The differences as you eluded to is that the maximum number of threads that can be running at any given time is equal to your number of cores.

To understand it in more details, you would need to know what the other two mean. WAITING would mean that a thread has been suspended on some object.

while(<condition holds>)
    obj.wait()

Here, the current thread is currently WAITING on obj's monitor. This would force that thread to become suspended in which the OS can schedule another thread to run.

TIMED_WAITING is simply suspending a thread for a certain amount of time.

So if a thread isn't waiting or sleeping it is considered running.

To give more insights from the documentation.

Thread state for a runnable thread. A
thread in the runnable state is
executing in the Java virtual machine
but it may be waiting for other
resources from the operating system
such as processor.

That last part is what I think you are looking for. Physically the OS cannot run more threads in parallel than the amount of the cores.
All 9 of your threads may run concurrently but only n will run in parallel (n being the number of cores).

Similar is true for Condition.await

Edit:

Sorry richs - Should've linked my resource http://download.oracle.com/javase/1.5.0/docs/api/java/lang/Thread.State.html#RUNNABLE

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