python线程之condition

时间：2021-12-23 15:47:08

cond = threading.Condition()

# 类似lock.acquire()

cond.acquire()

# 类似lock.release()

cond.release()

# 等待指定触发，同时会释放对锁的获取,直到被notify才重新占有琐。

cond.wait()

# 发送指定，触发执行

cond.notify()

以下分别为两个线程，三个线程，四个线程。可直接看四个线程的运行过程，更加直观，有时候用文字解释不如直接实验让人理解的快。

import threading,time

cond = threading.Condition()

#cond.acquire()

#cond.release()

#cond.wait()

#cond.notify()

def aa():

    print ('thread_aa get')

    cond.acquire()

    time.sleep(5)

    print ('thread_aa finished first job')

    cond.wait()#释放对锁的控制，好让别的进程acquire到

               #同时阻塞在此，等待得到锁的那个进程的先cond.notify后(cond.wait或cond.release)

    print ('thread_aa get again')

    time.sleep(5)

    print ('thread_aa finished all work')

    cond.notify()#告诉刚才释放锁的那个进程等通知吧,等我要么wait要么release

    cond.release()#释放锁

def bb():

    cond.acquire()

    print ('thread_bb get')

    cond.notify()#告诉刚才释放锁的那个进程等通知吧,等我要么wait要么release

    print ('依然是我bb在运行')

    time.sleep(5)

    print ('thread_bb finished first job')

    cond.wait()#释放对锁的控制，而后被阻塞的aa就可以执行了

            #同时阻塞在此，等待得到锁的aa的先cond.notify后(cond.wait或cond.release)

    print ('thread_aa get again')

    print ('thread_bb finished all works')

    cond.release()

a=threading.Thread(target=aa)

a.start()

time.sleep(2)

b=threading.Thread(target=bb)

b.start()
import threading,time

cond = threading.Condition()

def aa():

    cond.acquire()

    time.sleep(1)

    print ('aa1')

    cond.wait()

    time.sleep(1)

    print ('aa2')

    cond.notify()

    cond.wait()

    print ('aa3')

    cond.notify()

    cond.wait()

    print ('aa4')

    cond.release()

def bb():

    cond.acquire()

    print ('bb1')

    cond.wait()#没notify而直接wait，就是将对a的控制权抛出，但是自己的控

                           # 制权还在a那里,任意一个 acquire到锁的进城将得到对a的控

                             # 制权(除非他自己又抛出)，而这个acquire到锁的进程的控制

                            # 权在这个进程，如果这个进程在之后退出了，那么他控制的

                             # 进程的控制权将转交给控制他的进程

    print ('bb2')

    cond.notify()

    cond.release()

def cc():

    cond.acquire()

    print ('cc1')

    cond.notify()

    cond.wait()

    print ('cc2')

    cond.notify()

    cond.wait()

    print ('cc3')

    cond.notify()

    cond.release()

a=threading.Thread(target=aa)

a.start()

time.sleep(2)

b=threading.Thread(target=bb)

b.start()

time.sleep(2)

c=threading.Thread(target=cc)

c.start()

'''这是三个以上版本的，或许更加直观。运行结果:

aa1

bb1

cc1

aa2

bb2

cc2

aa3

cc3

aa4

'''
import threading,time

cond = threading.Condition()

def aa():

    cond.acquire()

    time.sleep(1)

    print ('aa1')

    cond.wait()

    time.sleep(1)

    print ('aa2')

    cond.wait()

    print ('aa3')

    cond.notify()

    cond.wait()

    print ('aa4')

    cond.release()

def bb():

    cond.acquire()

    print ('bb1')

    cond.wait()

    print ('bb2')

    cond.notify()

    cond.release()

def cc():

    cond.acquire()

    print ('cc1')

    cond.notify()

    cond.wait()

    print ('cc2')

    cond.notify()

    cond.wait()

    print ('cc3')

    cond.notify()

    cond.release()

def dd():

    cond.acquire()

    print ('dd1')

    cond.notify()

    cond.release()

a=threading.Thread(target=aa)

a.start()

time.sleep(2)

b=threading.Thread(target=bb)

b.start()

time.sleep(2)

c=threading.Thread(target=cc)

c.start()

time.sleep(2)

d=threading.Thread(target=dd)

d.start()

'''这是4个版本的,运行结果:

aa1

bb1

cc1

aa2

dd1

bb2

cc2

aa3

cc3

aa4

'''

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