【Java】如何查看某一Java进程中，当前有多少线程正在执行?

2021-01-05 19:28

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标签：line ota catch groups tac ESS 程序 efs 检测

我们先看一个最古老的多线程实现的服务端

public class SocketThread {

    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(9889);
        while (true) {
            Socket client = serverSocket.accept();

            new Thread(() -> {
                try {
                    System.out.println("client port :" + client.getPort());
                    InputStream inputStream = client.getInputStream();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
                    while (true) {
                        System.out.println(bufferedReader.readLine());
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }).start();
        }

    }

}

strace指令查看：

我们用【strace】指令检测一下：


-o：输出  到某个路径
-ff: 抓取这个程序所有线程

[root@bogon thread]# strace -ff -o /root/data/thread-group/ooxx java SocketThread   //程序对内核有没有发生什么系统调用

然后可以再thread-group目录中看到线程详情：

技术图片

jps进行查看

首先用【jps】指令查看一下进程详情：

[root@bogon thread-group]# jps
12485 Jps
12475 Loop

然后我们进入【Loop】进程，继续深入：

[root@bogon thread-group]# cd /proc/12475
[root@bogon 12475]# ls
attr        comm             fd        map_files   net            pagemap      schedstat  statm    wchan
autogroup   coredump_filter  fdinfo    maps        ns             patch_state  sessionid  status
auxv        cpuset           gid_map   mem         numa_maps      personality  setgroups  syscall
cgroup      cwd              io        mountinfo   oom_adj        projid_map   smaps      task
clear_refs  environ          limits    mounts      oom_score      root         stack      timers
cmdline     exe              loginuid  mountstats  oom_score_adj  sched        stat       uid_map

1》然后我们进入【task】目录，可以看到线程详情：

[root@bogon 12475]# cd task/
[root@bogon task]# ls
12475  12476  12477  12478  12479  12480  12481  12482  12483  12484
[root@bogon task]# ll
total 0
dr-xr-xr-x. 7 root root 0 May 27 10:08 12475
dr-xr-xr-x. 7 root root 0 May 27 10:08 12476
dr-xr-xr-x. 7 root root 0 May 27 10:08 12477
dr-xr-xr-x. 7 root root 0 May 27 10:08 12478
dr-xr-xr-x. 7 root root 0 May 27 10:08 12479
dr-xr-xr-x. 7 root root 0 May 27 10:08 12480
dr-xr-xr-x. 7 root root 0 May 27 10:08 12481
dr-xr-xr-x. 7 root root 0 May 27 10:08 12482
dr-xr-xr-x. 7 root root 0 May 27 10:08 12483
dr-xr-xr-x. 7 root root 0 May 27 10:08 12484