threading.Lock()
lock.acquire()
lock.release()
import threading
withlock=0
nolock=0
count=10000
lock=threading.Lock()
def inwithlock():
global withlock
for i in range(count):
lock.acquire()
withlock+=1
lock.release()
def dewithlock():
global withlock
for i in range(count):
lock.acquire()
withlock-=1
lock.release()
def innolock():
global nolock
for i in range(count):
nolock+=1
def denolock():
global nolock
for i in range(count):
nolock-=1
t1=threading.Thread(target=inwithlock)
t2=threading.Thread(target=dewithlock)
t3=threading.Thread(target=innolock)
t4=threading.Thread(target=denolock)
t1.start()
t2.start()
t3.start()
t4.start()
t1.join()
t2.join()
t3.join()
t4.join()
print("%s" % withlock)
print("%s" % nolock)
线程安全的操作
import threading
global var
count = 0
lock = threading.Lock()
Define a function for the thread
def print_time(threadName):
global count
c=0
with lock:
while(c<100):
c+=1
count+=1
print("{0}: set count to {1}".format( threadName, count) )
Create and run threads as follows
try:
threading.Thread( target=print_time, args=("Thread-1", ) ).start()
threading.Thread( target=print_time, args=("Thread-2", ) ).start()
threading.Thread( target=print_time, args=("Thread-3", ) ).start()
except Exception as e:
print("Error: unable to start thread")
RLOCK和LOCK的区别
1.2 死锁
Lock在下面的情形下会发生死锁
Lock.acquire()
Lock.acquire()
Lock.release()
Lock.release()
连续两次acquire请求，会导致死锁，因为第一次获得锁之后还没有释放，第二次再来申请，程序就阻塞在这里，导致第一次申请到的锁无法释放
1.3 可重入锁
RLock就不存在1.2中所提到的死锁
RLock.acquire()
RLock.acquire()
RLock.release()
RLock.release()
但是要保证，有多少次acquire就有多少次release
