是否有任何方法可以获得当前JVM中所有正在运行的线程的列表(包括不是由我的类启动的线程)?
是否也可以获得列表中所有线程的Thread和Class对象?
我希望能够通过代码来实现。
是否有任何方法可以获得当前JVM中所有正在运行的线程的列表(包括不是由我的类启动的线程)?
是否也可以获得列表中所有线程的Thread和Class对象?
我希望能够通过代码来实现。
当前回答
获取主线程启动的线程列表的代码片段:
import java.util.Set;
public class ThreadSet {
public static void main(String args[]) throws Exception{
Thread.currentThread().setName("ThreadSet");
for ( int i=0; i< 3; i++){
Thread t = new Thread(new MyThread());
t.setName("MyThread:"+i);
t.start();
}
Set<Thread> threadSet = Thread.getAllStackTraces().keySet();
for ( Thread t : threadSet){
if ( t.getThreadGroup() == Thread.currentThread().getThreadGroup()){
System.out.println("Thread :"+t+":"+"state:"+t.getState());
}
}
}
}
class MyThread implements Runnable{
public void run(){
try{
Thread.sleep(5000);
}catch(Exception err){
err.printStackTrace();
}
}
}
输出:
Thread :Thread[MyThread:2,5,main]:state:TIMED_WAITING
Thread :Thread[MyThread:0,5,main]:state:TIMED_WAITING
Thread :Thread[MyThread:1,5,main]:state:TIMED_WAITING
Thread :Thread[ThreadSet,5,main]:state:RUNNABLE
如果您需要包括系统线程在内的所有线程,这些线程还没有被您的程序启动,请删除以下条件。
if ( t.getThreadGroup() == Thread.currentThread().getThreadGroup())
现在输出:
Thread :Thread[MyThread:2,5,main]:state:TIMED_WAITING
Thread :Thread[Reference Handler,10,system]:state:WAITING
Thread :Thread[MyThread:1,5,main]:state:TIMED_WAITING
Thread :Thread[ThreadSet,5,main]:state:RUNNABLE
Thread :Thread[MyThread:0,5,main]:state:TIMED_WAITING
Thread :Thread[Finalizer,8,system]:state:WAITING
Thread :Thread[Signal Dispatcher,9,system]:state:RUNNABLE
Thread :Thread[Attach Listener,5,system]:state:RUNNABLE
其他回答
获取根线程组的句柄,像这样:
ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();
ThreadGroup parentGroup;
while ((parentGroup = rootGroup.getParent()) != null) {
rootGroup = parentGroup;
}
现在,在根组上重复调用enumerate()函数。第二个参数让你递归地获取所有线程:
Thread[] threads = new Thread[rootGroup.activeCount()];
while (rootGroup.enumerate(threads, true ) == threads.length) {
threads = new Thread[threads.length * 2];
}
注意我们如何反复调用enumerate(),直到数组大到足以包含所有条目。
是的,看一下如何获取线程列表。那页上有很多例子。
这是通过编程来实现的。如果你只是想在Linux上得到一个列表,至少你可以使用这个命令:
kill -3 processid
虚拟机将做一个线程转储到标准输出。
Apache Commons用户可以使用ThreadUtils。当前实现使用前面概述的线程组方法。
for (Thread t : ThreadUtils.getAllThreads()) {
System.out.println(t.getName() + ", " + t.isDaemon());
}
您可以从ThreadMXBean获得大量关于线程的信息。
调用静态的ManagementFactory.getThreadMXBean()方法来获得对MBean的引用。
public static void main(String[] args) {
// Walk up all the way to the root thread group
ThreadGroup rootGroup = Thread.currentThread().getThreadGroup();
ThreadGroup parent;
while ((parent = rootGroup.getParent()) != null) {
rootGroup = parent;
}
listThreads(rootGroup, "");
}
// List all threads and recursively list all subgroup
public static void listThreads(ThreadGroup group, String indent) {
System.out.println(indent + "Group[" + group.getName() +
":" + group.getClass()+"]");
int nt = group.activeCount();
Thread[] threads = new Thread[nt*2 + 10]; //nt is not accurate
nt = group.enumerate(threads, false);
// List every thread in the group
for (int i=0; i<nt; i++) {
Thread t = threads[i];
System.out.println(indent + " Thread[" + t.getName()
+ ":" + t.getClass() + "]");
}
// Recursively list all subgroups
int ng = group.activeGroupCount();
ThreadGroup[] groups = new ThreadGroup[ng*2 + 10];
ng = group.enumerate(groups, false);
for (int i=0; i<ng; i++) {
listThreads(groups[i], indent + " ");
}
}