在我的 https://www.yuque.com/infuq/default/dsag1h 文章中，對Java線程的狀態(tài)進(jìn)行了描述陕截，如下圖所示

圖片.png

此篇文章实撒，我們驗(yàn)證下淹真，當(dāng)線程進(jìn)行socket.read()時(shí)舍悯，線程的狀態(tài)是RUNNABLE

實(shí)驗(yàn)涉及三個(gè)文件, Server.java, Client.java, BusinessHandler.java

package com.infuq.bio;

import com.alibaba.druid.util.StringUtils;
import lombok.extern.slf4j.Slf4j;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.time.LocalDate;

public class BusinessHandler implements Runnable {

    private Socket socket;

    public BusinessHandler(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {

        BufferedReader reader = null;
        PrintWriter writer = null;
        try {
            reader = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            writer = new PrintWriter(this.socket.getOutputStream(), true);

            while (true) {
                System.out.println("準(zhǔn)備接收客戶端數(shù)據(jù)");
                String body = reader.readLine();
                if (StringUtils.isEmpty(body)) {
                    break;
                }
                System.out.println("接收客戶端數(shù)據(jù): " + body);

                writer.println(body + " = " + LocalDate.now());
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (reader != null) {
                    reader.close();
                }
                if (writer != null) {
                    writer.close();
                }
                if (this.socket != null) {
                    this.socket.close();
                    this.socket = null;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

package com.infuq.bio;

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {

    private static final int LISTEN_PORT = 8080;
    private static int index = 1;

    public static void main(String[] args) throws Exception {
        ServerSocket server = new ServerSocket(LISTEN_PORT);

        while (true) {
            Socket socket = server.accept();

            BusinessHandler serverHandler = new BusinessHandler(socket);
            new Thread(new BusinessHandler(socket), "BusinessHandlerThread-" + (index++)).start();
        }
    }
}

package com.infuq.bio;

import lombok.extern.slf4j.Slf4j;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Random;

public class Client {

    private static int PORT = 8080;
    private static String HOST = "127.0.0.1";

    public static void main(String[] args) {

        request();

    }

    private static void request() {
        Socket socket = null;
        BufferedReader reader = null;
        PrintWriter writer = null;
        try {
            socket = new Socket(HOST, PORT);

            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new PrintWriter(socket.getOutputStream(), true);

            String[] operators = {"+", "-", "*", "/"};
            Random random = new Random(System.currentTimeMillis());
            String expression = random.nextInt(10) + operators[random.nextInt(4)] + (random.nextInt(10) + 1);
            writer.println(expression);

            System.out.println("接收服務(wù)端數(shù)據(jù): " + reader.readLine());
            // 暫時(shí)讓客戶端不退出
            Thread.sleep(3600 * 1000);

        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (reader != null) {
                    reader.close();
                }
                if (writer != null) {
                    writer.close();
                }
                if (socket != null) {
                    socket.close();
                    socket = null;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

目錄結(jié)構(gòu)如下圖所示

圖片.png

分別進(jìn)行編譯
[infuq: bio]# javac -d . Client.java
[infuq: bio]# javac -d . BusinessHandler.java
[infuq: bio]# javac -d . Server.java

編譯后如下圖

圖片.png

首先執(zhí)行服務(wù)端
[infuq: bio]# strace -ff -o out java com.infuq.bio.Server

strace命令可以用于追蹤系統(tǒng)調(diào)用

再執(zhí)行客戶端
[infuq: bio]# java com.infuq.bio.Client

通過jps 查看服務(wù)端的進(jìn)程號(hào)印颤， 進(jìn)程號(hào)1515

圖片.png

通過jstack 1515 > 1515.txt 導(dǎo)出線程堆棧信息
查看堆棧信息

圖片.png

可以得知姆另，服務(wù)端線程在處理IO時(shí)阻塞在socket的read方法臼予，線程狀態(tài)是RUNNABLE.
它的nid=ox617，也就是十進(jìn)制1559胯甩， 我們之前執(zhí)行服務(wù)端時(shí)使用的strace會(huì)創(chuàng)建出很多以線程ID命名的文件昧廷，如下圖

圖片.png

通過tail -f out.1559查看

圖片.png

線程阻塞在系統(tǒng)調(diào)用recvfrom方法， 也就是上面我們所說的socket的read方法

而且如果你通過ps -Lf 1515, 那么你看到的線程1559的狀態(tài)是Sleep狀態(tài)偎箫， 也就是說木柬，對于socket進(jìn)行read時(shí)，如果發(fā)生阻塞淹办，那么對應(yīng)的Java線程的狀態(tài)是RUNNABLE眉枕，而對應(yīng)的底層操作系統(tǒng)的線程的狀態(tài)是Sleep， Java線程的狀態(tài)本身和底層操作系統(tǒng)線程的狀態(tài)不是一一對等的