Python 多執行緒

python的標準庫提供了兩個模組：thread和threading，thread是低階模組，threading是高階模組，對thread進行了封裝。絕大多數情況下，我們只需要使用threading這個高階模組。

啟動乙個執行緒就是把乙個函式傳入並建立thread例項，然後呼叫start()開始執行：

import time,threading
defloop
():print
'thread %s is running...'%threading.current_thread().name
n = 0
while n<5:
n= n+1
print
'thread %s >>> %s'%(threading.current_thread().name,n)
time.sleep(1)
print
'thread %s end.' %threading.current_thread().name
print
'thread %s in running...' % threading.current_thread().name
t = threading.thread(target = loop,name = 'loopthread')
t.start()
t.join()
print
'thread %s end.' %threading.current_thread().name

輸出結果：

thread mainthread is running…

thread loopthread is running…

thread loopthread >>> 1

thread loopthread >>> 2

thread loopthread >>> 3

thread loopthread >>> 4

thread loopthread >>> 5

thread loopthread ended.

thread mainthread ended.

由於任何程序預設就會啟動乙個執行緒，我們把該執行緒稱為主線程，主線程又可以啟動新的執行緒，python的threading模組有個current_thread()函式，它永遠返回當前執行緒的例項。主線程例項的名字叫mainthread，子執行緒的名字在建立時指定，我們用loopthread命名子執行緒。名字僅僅在列印時用來顯示，完全沒有其他意義，如果不起名字python就自動給執行緒命名為thread-1，thread-2……

import threading
# 3.lock
# 假定這是你的銀行存款:
balance = 0
lock = threading.lock()
defchange_it
(n):
# 先存後取，結果應該為0:
global balance
balance = balance + n
balance = balance - n
defrun_thread
(n):
for i in range(100000):
lock.acquire()
try:
change_it(n)
finally:
lock.release()
t1 = threading.thread(target=run_thread, args=(5,))
t2 = threading.thread(target=run_thread, args=(8,))
t1.start()
t2.start()
t1.join()
t2.join()
print balance

from random import randint
from time import sleep
from queue import queue
from mythread import mythread
defwriteq
(queue):
print
'producing object for q...',
queue.put('***', 1)
print
"size now", queue.qsize()
defreadq
(queue):
val = queue.get(1)
print
'consumed object from q... size now', \
queue.qsize()
defwriter
(queue, loops):
for i in range(loops):
writeq(queue)
sleep(randint(1, 3))
defreader
(queue, loops):
for i in range(loops):
readq(queue)
sleep(randint(2, 5))
funcs = [writer, reader]
nfuncs = range(len(funcs))
defmain
():    nloops = randint(2, 5)
q = queue(32)
threads = 
for i in nfuncs:
t = mythread(funcs[i], (q, nloops), \
funcs[i].__name__)
for i in nfuncs:
threads[i].start()
for i in nfuncs:
threads[i].join()
print
'all done'
if __name__ == '__main__':
main()

starting writer at: mon mar 06 16:34:51 2017

add for q… size now= 1

starting reader at: mon mar 06 16:34:51 2017

sub from q… size now= 0

add for q… size now= 1

sub from q… size now= 0

add for q… size now= 1

add for q… size now= 2

writer finished at: mon mar 06 16:34:57 2017

sub from q… size now= 1

sub from q… size now= 0

reader finished at: mon mar 06 16:35:06 2017

all done

參考文獻：

Python 多執行緒

python多執行緒 python多執行緒

python多執行緒詳解 Python多執行緒詳解

python程式多執行緒 PYTHON多執行緒

Python 多執行緒

python多執行緒 python多執行緒

python多執行緒詳解 Python多執行緒詳解

python程式多執行緒 PYTHON多執行緒

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