多線程

多線程Threading

多線程之間的資源是共享的，多線程之間是併發的

多線程的實現

import threading
import time

def music(name):
    print('%s begin to listen to music %s'%(name,time.ctime()))
    time.sleep(3)
    print('%s end to listen to music %s'%(name,time.ctime()))

def game(name):
    print('%s begin to play game %s'%(name,time.ctime()))
    time.sleep(5)
    print('%s end to play game %s'%(name,time.ctime()))

if __name__ == '__main__':
    t1=threading.Thread(target=music,args=('alex',))#實例化多線程
    t2=threading.Thread(target=game,args=('alex',))

    t1.start()#開始執行多線程
    t2.start()

    print('end....') #注意時間只要5秒就完成
'''alex begin to listen to music Tue Apr 17 21:32:50 2018
alex begin to play game Tue Apr 17 21:32:50 2018
end....
alex end to listen to music Tue Apr 17 21:32:53 2018
alex end to play game Tue Apr 17 21:32:55 2018'''

join

import threading
import time

def music(name):
    print('%s begin to listen to music %s'%(name,time.ctime()))
    time.sleep(3)
    print('%s end to listen to music %s'%(name,time.ctime()))

def game(name):
    print('%s begin to play game %s'%(name,time.ctime()))
    time.sleep(5)
    print('%s end to play game %s'%(name,time.ctime()))

if __name__ == '__main__':
    t1=threading.Thread(target=music,args=('alex',))#實例化多線程
    t2=threading.Thread(target=game,args=('alex',))

    t1.start()#開始執行多線程
    t2.start()

    t1.join() #join方法是讓主線程等待子線程t1結束後才繼續執行主線程
    t2.join()  
    print('end....') 
'''alex begin to listen to music Tue Apr 17 21:39:23 2018
alex begin to play game Tue Apr 17 21:39:23 2018
alex end to listen to music Tue Apr 17 21:39:26 2018
alex end to play game Tue Apr 17 21:39:28 2018
end....'''

若改成

if __name__ == '__main__':
    t1=threading.Thread(target=music,args=('alex',))#實例化多線程
    t2=threading.Thread(target=game,args=('alex',))

    t1.start()#開始執行多線程
    t2.start()

    t1.join() #join方法是讓主線程等待子線程t1結束後才繼續執行主線程

    #t2.join()  
    print('end....') 
'''alex begin to listen to music Tue Apr 17 21:41:11 2018
alex begin to play game Tue Apr 17 21:41:11 2018
alex end to listen to music Tue Apr 17 21:41:14 2018
end....
alex end to play game Tue Apr 17 21:41:16 2018'''
#t1在執行完畢後會立即執行print，然後等待執行t2

Setdaemon

import threading
import time

def music(name):
    print('%s begin to listen to music %s'%(name,time.ctime()))
    time.sleep(3)
    print('%s end to listen to music %s'%(name,time.ctime()))

def game(name):
    print('%s begin to play game %s'%(name,time.ctime()))
    time.sleep(5)
    print('%s end to play game %s'%(name,time.ctime()))


if __name__ == '__main__':
    t1=threading.Thread(target=music,args=('alex',))
    t2=threading.Thread(target=game,args=('alex',))
    t2.setDaemon(True) #必須在start前設置，一旦主線程結束，對應的子線程也結束
    t1.start()
    t2.start()
    print('end....')
'''
alex begin to listen to music Thu Apr 19 15:22:42 2018
alex begin to play game Thu Apr 19 15:22:42 2018
end....
alex end to listen to music Thu Apr 19 15:22:45 2018
'''
#在打印end...後還要等待t1的運行，當t1運行完後，主線程纔算結束，t2也跟着結束

若改成

if __name__ == '__main__':
    t1=threading.Thread(target=music,args=('alex',))
    t2=threading.Thread(target=game,args=('alex',))
    t1.setDaemon(True) #必須在start前設置，一旦主線程結束，對應的子線程也結束
    t1.start()
    t2.start()
    print('end....')
'''
alex begin to listen to music Thu Apr 19 15:26:46 2018
alex begin to play game Thu Apr 19 15:26:46 2018
end....
alex end to listen to music Thu Apr 19 15:26:49 2018
alex end to play game Thu Apr 19 15:26:51 2018
'''
#在打印end...之後要等待t2運行，但t1在t2運行結束之前已經運行，故當t2結束運行，主線程結束時t1也運行完畢

線程相關的其他方法

#Thread實例對象的方法
  # isAlive(): 返回線程是否活動的。
  # getName(): 返回線程名。
  # setName(): 設置線程名。

#threading模塊提供的一些方法：
  # threading.currentThread(): 返回當前的線程變量。
  # threading.enumerate(): 返回一個包含正在運行的線程的list。正在運行指線程啓動後、結束前，不包括啓動前和終止後的線程。
  # threading.activeCount(): 返回正在運行的線程數量，與len(threading.enumerate())有相同的結果。

from threading import Thread
import threading


def work():
    import time
    time.sleep(3)
    print(threading.current_thread().getName())


if __name__ == '__main__':
    #在主進程下開啓線程
    t=Thread(target=work)
    t.start()

    print(threading.current_thread().getName())
    print(threading.current_thread()) #主線程
    print(threading.enumerate()) #連同主線程在內有兩個運行的線程
    print(threading.active_count())
    print('主線程/主進程')

    '''
    打印結果:
    MainThread
    <_MainThread(MainThread, started 140735268892672)>
    [<_MainThread(MainThread, started 140735268892672)>, <Thread(Thread-1, started 123145307557888)>]
    主線程/主進程
    Thread-1
    '''

主線程等待子線程結束

from threading import Thread
import time
def sayhi(name):
    time.sleep(2)
    print('%s say hello' %name)

if __name__ == '__main__':
    t=Thread(target=sayhi,args=('alex',))
    t.start()
    t.join()
    print('主線程')
    print(t.is_alive())
    '''
    alex say hello
    主線程
    False
    '''