哪个Java线程在占用CPU? [英] Which Java thread is hogging the CPU?

问题描述

假设您的Java程序占用了100％的CPU.它有50个线程.您需要查找哪个线程有罪.我没有找到可以提供帮助的工具.当前，我使用以下非常耗时的例程:

Let's say your Java program is taking 100% CPU. It has 50 threads. You need to find which thread is guilty. I have not found a tool that can help. Currently I use the following very time consuming routine:

1. 运行jstack <pid>，其中pid是Java进程的进程ID.找到它的简单方法是运行JDK中包含的另一个实用程序-jps.最好将jstack的输出重定向到文件.
2. 搜索可运行"线程.跳过那些在套接字上等待的对象(由于某些原因，它们仍被标记为可运行).
3. 重复步骤1和2两次，看看是否可以找到图案.

1. Run jstack <pid>, where pid is the process id of a Java process. The easy way to find it is to run another utility included in the JDK - jps. It is better to redirect jstack's output to a file.
2. Search for "runnable" threads. Skip those that wait on a socket (for some reason they are still marked runnable).
3. Repeat steps 1 and 2 a couple of times and see if you can locate a pattern.

或者，您可以在Eclipse中附加到Java进程并尝试逐个挂起线程，直到遇到占用CPU的线程.在单CPU机器上，您可能需要首先降低Java进程的优先级才能移动.即便如此，由于超时，Eclipse通常仍无法连接到正在运行的进程.

Alternatively, you could attach to a Java process in Eclipse and try to suspend threads one by one, until you hit the one that hogs CPU. On a one-CPU machine, you might need to first reduce the Java process's priority to be able to move around. Even then, Eclipse often isn't able to attach to a running process due to a timeout.

我希望Sun的visualvm工具能够做到这一点.

I would have expected Sun's visualvm tool to do this.

有人知道更好的方法吗?

Does anybody know of a better way?

推荐答案

尝试查看

Try looking at the Hot Thread Detector plugin for visual VM -- it uses the ThreadMXBean API to take multiple CPU consumption samples to find the most active threads. It's based on a command-line equivalent from Bruce Chapman which might also be useful.

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