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I have a Java application where some threads are created (via new Thread()). Using ps I can see they have different thread IDs (LWP column) and I would like to obtain those IDs from within the Java application.

In most of the posts related to this topic that I have found (e.g., this one), the solution is to use ManagementFactory.getRuntimeMXBean().getName().

Using that method, however, gives me the PID of the main thread (even if I call it from one of the threads), so it is not really solving my problem.

Is there any way to obtain the thread ID for every single Thread created by an application?

Would it be possible to use JNI to accomplish it? If somehow I could interface to a C function where I could call syscall(__NR_gettid), that could solve my problem. I really do not care about portability, so I am totally okay with a solution that would only work for a Linux machine.

UPDATE: I have actually solved my problem by using JNI. Details are explained in my answer. Thank you all for your suggestions/comments.

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2 に答える 2

11

最終的に、私の問題を解決するには JNI の方法が最適であることがわかりました。参考として、コードとビルド手順を投稿します (ウィキペディアの例に基づいています)。

C コードへのインターフェースを担当する Java クラス ( GetThreadID.java):

public class GetThreadID {
    public static native int get_tid();

    static {
        System.loadLibrary("GetThreadID");
    }
}

スレッド ID の取得を担当する C ファイル ( GetThread.c):

#include <jni.h>
#include <syscall.h>
#include "GetThreadID.h"

JNIEXPORT jint JNICALL
Java_GetThreadID_get_1tid(JNIEnv *env, jobject obj) {
    jint tid = syscall(__NR_gettid);
    return tid;
}

GetThreadIDクラスの使用方法の例:

class Main {
    public static void main(String[] args) {
        int tid = GetThreadID.get_tid();
        System.out.println("TID=" + tid);
    }
}

そして最後に、ビルド手順 (javah自動的に生成されますGetThreadID.h):

JAVA_HOME=$(readlink -f /usr/bin/javac | sed "s:bin/javac::")
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:.
javac GetThreadID.java
javah GetThreadID

gcc -I${JAVA_HOME}/include -fPIC -shared GetThreadID.c -o libGetThreadID.so
javac Main.java
java Main
于 2012-06-27T13:47:58.590 に答える
3

このブログ投稿は、JavaスレッドIDからLWPIDにマッピングする方法を提供します。

その要点は、NLWPIDがJavaスレッドIDにマップされているようです。

于 2012-06-27T10:55:23.560 に答える