python 并行开发

四、并行开发

标签（空格分隔）： 未分类

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并行

串行与并行
阻塞与非阻塞任务
共享与冲突
多线程与多进程的区别和特点

多进程开发

 Linux、unix平台专属

Fork

wait

Waitpid

#coding=UTF-8
import os
import time
def myfork():
    a = 1
    pid = os.fork()
    if pid == 0:
        print "this is child %d--%d %d" %(pid, os.getpid(), os.getppid())
        time.sleep(1)
        print a+1
        #while True:
        #    pass
    else:
        status = os.waitpid(pid, 0)   ##将此行注释，比较执行结果
        #status = os.waitpid(pid. 1)
        print "this is parent %d--%d %d" %(pid, os.getpid(), os.getppid())
        print a+3
if __name__ == '__main__' : 
    myfork()

pipe和singal

进程间管道通信

#coding=UTF-8
import os
import time
def onsignal_term(a, b):
    print 'over'
signal.signal(signal.SIGTERM,onsignal_term)  #将终端信号注入到系统信号中
def myfork():
    r, w = os.pipe()
    a = 1
    pid = os.fork()
    if pid == 0:
        os.close(r)
        w = os.write(w, 'w')
        print "this is child %d--%d %d" %(pid, os.getpid(), os.getppid())
        while True:
            a = a+1
            if a>100:
                os.kill(os.getppid, signal.SIGTERM)
            os.write(w,str(a))
            #w.write(a)
            print '\n'
        w.close()
    else:
        os.close(w)
        r = os.fdopen(r)
        print r.read() 
        r.close()
        print "this is parent %d--%d %d" %(pid, os.getpid(), os.getppid())
        status = os.waitpid(pid, 1)
if __name__ == '__main__' : 
    myfork()

守护进程

守护进程方式

#coding=UTF-8
import os
import sys
def daemon_test():
    pid = os.fork()
    if pid > 0:
        sys.exit(0)
    os.setsid()    #脱离终端
    os.umask(0)
    pid = os.fork()
    if pid > 0:
        sys.exit(0)
    f = open('test.txt', 'w')
    a =1
    while True:
        a=a+1
        f.write(str(a))
    f.close()
if __name__=='__main__':
    daemon_test()

运行结果：

ls -lh   //-rw-rw-rw-.  1 root root 171M May 29 01:29 test.txt
tail -f test.txt 
ps -ef daemon 
kill *****   //杀死守护进程

多线程开发

 Thread

import thread 
import time
def funt(no, a):
    while True:
        a =a+1
        print 'Thread no %d = %d, '%(no, a)
def test():
    thread.start_new_thread(funt, (1,2))
    thread.start_new_thread(funt, (2,2))
    time.sleep(20)   #注释看看结果，父进程会立即回收，派生的两个子线程马上就会被回收
if __name__=='__main__':
    test()

 共享变量与临界资源:多线程操作全局变量

import thread 
import time
c=1
def funt(no, a):
    global c  
    while True:
        time.sleep(1)
        c =c+1
        print 'Thread no %d = %d, '%(no, c)
def test():
    thread.start_new_thread(funt, (1,2))
    thread.start_new_thread(funt, (2,2))
    time.sleep(20)
if __name__=='__main__':
    test()

 Threading 面向对象编程 
定义一个单线程类

#coding=UTF-8
import threading 
import time
count = 0
class aa(threading.Thread):  #aa由thread对象继承而来
    def __init__(self, no, interval): #构造函数
        threading.Thread.__init__(self) #初始化基类的构造函数
        self.no = no
        self.interval = interval
        self.isstop = False
    def run(self):       #重载方法
        global count
        while not self.isstop:
            count+=1
            print 'thread %d = %d' % (self.no, count)
            time.sleep(self.interval)
    def stop(self):
        self.isstop = True
def factory():
    t1 = aa(1,1)
    t1.start()
    time.sleep(20)
    t1.stop()
if __name__=="__main__":
    factory()

 锁机制:多线程加锁操作

#coding=UTF-8
import threading 
import time
mylock = threading.RLock()  #读锁
count = 0
class aa(threading.Thread):  #aa由thread对象继承而来
    def __init__(self, no, interval): #构造函数
        threading.Thread.__init__(self) #初始化基类的构造函数
        self.no = no
        self.interval = interval
        self.isstop = False
    def run(self):       #重载方法
        global count
        a =0
        while a<10:
            mylock.acquire()
            count+=1
            mylock.release()
            print 'thread %d = %d' % (self.no, count)
            #time.sleep(self.interval)
            a+=1
    def stop(self):
        self.isstop = True
def factory():
    t1 = aa(1,1)
    t1.start()
    t2 = aa(2,2)
    t2.start()
    time.sleep(20)
    t1.stop()
    t2.stop()
if __name__=="__main__":
    factory()