python執行緒學習筆記

1.執行緒建立   

1.1函式建立執行緒

def helloworld():

time.sleep(2)
print("hello world")
t = threading.thread(target=helloworld)
t.start()
print("main thread")

class helloworld(threading.thread):

def __init__(self,id):
self.id = id
super(helloworld,self).__init__()
def run(self):
time.sleep(2)
print("thread %d helloworld" % self.id)
for i in range(5):
t = helloworld(i)
t.start()
print("main thread")

t.start()  啟動執行緒活動

t.join()  保證當前執行緒執行完成以後，再執行其他執行緒。

import threading,time

count = 0
def adder():
global count
count = count + 1
time.sleep(0.1)
count = count + 1
threads = 
for i in range(100):
thread = threading.thread(target=adder)
thread.start()
for thread in threads:
thread.join()
print(count)

3.執行緒鎖

函式加鎖

import threading

import time
count = 0
def adder(addlock):
global count
addlock.acquire()
count = count +1
addlock.release()
time.sleep(0.1)
addlock.acquire()
count = count + 1
addlock.release()
addlock = threading.lock()
threads  = 
for i in range(100):
thread = threading.thread(target=adder,args = (addlock,))
thread.start()
for thread in threads:
thread.join()
print(count)

import threading

import time
count = 0
def adder(addlock):
global count
with addlock:
count = count +1
time.sleep(0.1)
with addlock:
count = count + 1
addlock = threading.lock()
threads = 
for i in range(100):
thread = threading.thread(target=adder,args = (addlock,))
thread.start()
for thread in threads:
thread.join()
print(count)

import threading

import time
class helloworld(threading.thread):
count =0
addlock = threading.lock()
def run(self):
with helloworld.addlock:
helloworld.count +=1
time.sleep(0.5)
with helloworld.addlock:
helloworld.count += 1
threads = 
for i in range(5):
t = helloworld()
t.start()
for t in threads:
t.join()
print(helloworld.count)

同時訪問5個執行緒。

import time

import threading
semaphore = threading.semaphore(5)   #新增乙個計數器
def foo():
semaphore.acquire()    #計數器獲得鎖
time.sleep(2)   #程式休眠2秒
print("ok",time.ctime())
semaphore.release()    #計數器釋放鎖
for i in range(20):
t1=threading.thread(target=foo,args=()) #建立執行緒
t1.start()  #啟動執行緒

import threading

import queue
import time
numconsumers = 2
numprofucers = 2
nummessages  = 4
lock = threading.lock()
dataqueue = queue.queue()
def producer(idnum):
for msgnum in range(nummessages):
dataqueue.put("producer id=%d,count=%d" % (idnum,msgnum))
def consumer(idnum):
while not dataqueue.empty():
data = dataqueue.get(block=false)
with lock:
print("consumer",idnum,"got =>",data)
time.sleep(0.1)
if __name__ == '__main__':
consumerthreads = 
producerthreads = 
for i in range(numprofucers):
t = threading.thread(target = producer,args = (i,))
t.start()
print(dataqueue.qsize())
for i in range(numconsumers):
t = threading.thread(target=consumer,args =(i,))
t.start()
for t in producerthreads:
t.join()
for t in consumerthreads:
t.join()

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