在我的 https://www.yuque.com/infuq/default/dsag1h 文章中，对Java线程的状态进行了描述，如下图所示
此篇文章，我们验证下，当线程进行socket.read()时，线程的状态是RUNNABLE
实验涉及三个文件, Server.java, Client.java, BusinessHandler.java
package com.infuq.bio;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("准备接收客户端数据");
String body = reader.readLine();
if (body == null || body.length() == 0) {
break;
}
System.out.println("接收客户端数据: " + 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 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("接收服务端数据: " + reader.readLine());
// 暂时让客户端不退出
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();
}
}
}
}
目录结构如下图所示
分别进行编译
[infuq: bio]# javac -d . Client.java
[infuq: bio]# javac -d . BusinessHandler.java
[infuq: bio]# javac -d . Server.java
编译后如下图
首先执行服务端
[infuq: bio]# strace -ff -o out java com.infuq.bio.Server
strace命令可以用于追踪系统调用
再执行客户端
[infuq: bio]# java com.infuq.bio.Client
通过jps 查看服务端的进程号， 进程号1515
通过jstack 1515 > 1515.txt 导出线程堆栈信息
查看堆栈信息
可以得知，服务端线程在处理IO时阻塞在socket的read方法，线程状态是RUNNABLE.
它的nid=ox617，也就是十进制1559， 我们之前执行服务端时使用的strace会创建出很多以线程ID命名的文件，如下图
通过tail -f out.1559查看
线程阻塞在系统调用recvfrom方法， 也就是上面我们所说的socket的read方法
而且如果你通过ps -Lf 1515, 那么你看到的线程1559的状态是Sleep状态， 也就是说，对于socket进行read时，如果发生阻塞，那么对应的Java线程的状态是RUNNABLE，而对应的底层操作系统的线程的状态是Sleep， Java线程的状态本身和底层操作系统线程的状态不是一一对等的