多任务编程-线程

##线程
from threading import Thread

def func(a):
print(a)

p = Thread(target=func, args=('a',))
p.setDaemon(True)
p.start()
p.join()

from threading import Thread, Event

e = Event()
e.wait()
e.set()

线程同步互斥
from threading import Thread, Event

e = Event()

def func(a):
e.wait()
print(a)

def func1(b):
e.set()
print(b)

p = Thread(target=func, args=('a',))
p1 = Thread(target=func1, args=('b',))

p.start()
p1.start()

p.join()

线程上锁 共有变量修改,用全局变量,且多线程抢夺,那个线程抢到使用,使用完让出给下个线程使用
上锁/解锁 变量上锁后,下一个上锁阻塞必须等待解锁后才可以进行
from threading import Thread, Lock

l = Lock()

c = 100

def func(a):
l.acquire()
global c
c += a
print(c)
l.release()

def func1(b):
l.acquire()
global c
c += c
print(c)
l.release()

p = Thread(target=func, args=(1,))
p1 = Thread(target=func1, args=(1,))

p.start()
p1.start()

p.join()

### with
with l:
xxx
xxx
相当与
l.acquire()
xxx
xxx
l.release()