python创建多进程/多线程

#!/usr/bin/python

import os, time

print "Before the fork, my PID is", os.getpid()

if os.fork():
    print "I am the parent, my PID is", os.getpid()
else:
    print "I am the child, my PID is", os.getpid()

time.sleep(2)
print "Hello from both of us"

运行结果如下

root # ./server.py
Before the fork, my PID is 3161
I am the child, my PID is 3162
I am the parent, my PID is 3161
Hello from both of us
Hello from both of us

子进程终止时，需要调用wait函数，不然系统资源会被大堆zombie进程消耗掉。子进程结束时会发出SIGCHLD信号，用信号解决zombie或者poll轮询
os.fork需要在支持fork函数的系统中运行。

import threading, time
import sys

def threadcode(count):
    sys.stdout.write("I am the new thread %s\n" %
                     threading.currentThread().getName())
    time.sleep(count)

newThread = threading.Thread(target = threadcode, name = "ChildThread" , args = [2])
newThread.setDaemon(1)
newThread.start()

sys.stdout.write("I am the main thread %s\n" %
                 threading.currentThread().getName())
time.sleep(2)

newThread.join()

为了在多个线程之间共享资源，可以引入锁，信号量等机制。用线程机制可以轻松地编写支持多个并发的服务器端。

关于异步IO的资料参照Python网络编程基础相关章节

java线程创建方式如下：

一，Thread创建线程

package com.ciaos;

public class Test extends Thread {
	public void run(){
		System.out.println("thread start");
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println("thread end");
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("main start");
		Thread a = new Test();
		a.start();
		System.out.println("main end");
	}
}

二，Runnable接口创建线程
package com.ciaos;

public class Test implements Runnable {
	public void run(){
		System.out.println("thread start");
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		System.out.println("thread end");
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		System.out.println("main start");
		Runnable rb = new Test();
		Thread a = new Thread(rb);
		a.start();
		System.out.println("main end");
	}
}

python创建多进程/多线程

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