Python多线程中阻塞(join)与锁(Lock)使用误区解析

threads = [Thread() for i in range(5)]
for thread in threads:
 thread.start()
 thread.join()

threads = [Thread() for i in range(5)]
for thread in threads:
 thread.start()
for thread in threads:
 thread.join()

for thread in threads:
 thread.start()
while 1:
 if thread_num == 0:
 break
 time.sleep(0.01)

# -*- coding: utf-8 -*-

import threading
import time
count = 0

class Counter(threading.Thread):
 def __init__(self, name):
 self.thread_name = name
 super(Counter, self).__init__(name=name)

 def run(self):
 global count
 for i in xrange(100000):
  count = count + 1


counters = [Counter('thread:%s' % i) for i in range(5)]
for counter in counters:
 counter.start()

time.sleep(5)
print 'count=%s' % count

# -*- coding: utf-8 -*-

import threading
import time

count = 0
lock = threading.Lock()


class Counter(threading.Thread):
 def __init__(self, name):
 self.thread_name = name
 self.lock = threading.Lock()
 super(Counter, self).__init__(name=name)

 def run(self):
 global count
 global lock
 for i in xrange(100000):
  lock.acquire()
  count = count + 1
  lock.release()


counters = [Counter('thread:%s' % i) for i in range(5)]

for counter in counters:
 counter.start()

time.sleep(5)
print 'count=%s' % count

# -*- coding: utf-8 -*-

import threading
import time

count = 0
# lock = threading.Lock() # 正确的声明位置

class Counter(threading.Thread):
 def __init__(self, name):
 self.thread_name = name
 self.lock = threading.Lock() # 错误的声明位置
 super(Counter, self).__init__(name=name)

 def run(self):
 global count
 for i in xrange(100000):
  self.lock.acquire()
  count = count + 1
  self.lock.release()


counters = [Counter('thread:%s' % i) for i in range(5)]

for counter in counters:
 print counter.thread_name
 counter.start()

time.sleep(5)
print 'count=%s' % count