Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
679 views
in Technique[技术] by (71.8m points)

performance - Which method is the least obtrusive for generating thread dumps in java?

I am aware of the following methods for generating thread dumps in java:

  • kill -3
  • jstack
  • JMX from inside the JVM
  • JMX remote
  • JPDA (remote)
  • JVMTI (C API)

Of these methods, which is the least detrimental to the JVM's performance?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

If you just need to dump all stack traces to stdout, kill -3 and jstack should be the cheapest. The functionality is implemented natively in JVM code. No intermediate structures are created - the VM prints everything itself while it walks through the stacks.

Both commands perform the same VM operation except that signal handler prints stack traces locally to stdout of Java process, while jstack receives the output from the target VM through IPC (Unix domain socket on Linux or Named Pipe on Windows).

jstack uses Dynamic Attach mechanism under the hood. You can also utilize Dynamic Attach directly if you wish to receive the stack traces as a plain stream of bytes.

import com.sun.tools.attach.VirtualMachine;
import sun.tools.attach.HotSpotVirtualMachine;
import java.io.InputStream;

public class StackTrace {

    public static void main(String[] args) throws Exception {
        String pid = args[0];
        HotSpotVirtualMachine vm = (HotSpotVirtualMachine) VirtualMachine.attach(pid);

        try (InputStream in = vm.remoteDataDump()) {
            byte[] buf = new byte[8000];
            for (int bytes; (bytes = in.read(buf)) > 0; ) {
                System.out.write(buf, 0, bytes);
            }
        } finally {
            vm.detach();
        }
    }
}

Note that all of the mentioned methods operate in a VM safepoint anyway. This means that all Java threads are stopped while the stack traces are collected.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...