python - 线程错误 : AttributeError: 'NoneType' object has no attribute '_initialized'

Question

我正在尝试学习 Python 3 上的线程。我做了一个示例代码:

import time 
import threading

def myfunction(string,sleeptime,lock,*args):
  count = 0
  while count < 2:
    #entering critical section
    lock.acquire()
    print(string, " Now sleeping after Lock acquired for ",sleeptime)
    time.sleep(sleeptime)
    print(string, " Now releasing lock and sleeping again.\n",time.ctime(time.time()))
    lock.release()
    #exiting critical section
    time.sleep(sleeptime)
    count+=1
    #threading.Thread.daemon=True

if __name__!="__main__":
  lock = threading.Lock()
  try:
    threading.Thread.start(myfunction("Thread Nº 1",2,lock))
    threading.Thread.start(myfunction("Thread Nº 2",2,lock))
  except:
    raise

  while 1:pass

它部分起作用。当它到达 while<2 loop ，它返回错误:

Traceback (most recent call last):
  File "python", line 22, in <module>
AttributeError: 'NoneType' object has no attribute '_initialized'

并且从不执​​行第二个线程调用。

我该怎么做才能纠正这个问题？

谢谢大家!

Answer 1

您正在使用 Thread完全错误。首先，您没有调用 Thread 构造函数(即你的代码必须有 threading.Thread(<something>) 来创建新的 Thread 实例)。其次，您正在调用 myfunction在 main 线程中使用参数，而不是在新线程中。第三，该函数的返回值(隐式 None )作为隐式 self 传递。未绑定(bind)的参数 Thread.start方法!

正确的做法是

t1 = threading.Thread(target=myfunction, args=("Thread Nº 1", 2, lock))
t1.start()

同样适用于 t2 .此外，如果您这样做，您将保留对 Thread 的引用。对象，您可以替换 while 1: pass与

t1.join()
t2.join()
print("Both threads exited, exiting.")

或者同样地:

for t in [t1, t2]:
    t.join()
print("Both threads exited, exiting.")

经过这些修改，程序将输出

Thread Nº 1  Now sleeping after Lock acquired for  2
Thread Nº 1  Now releasing lock and sleeping again.
 Mon Jun 26 17:42:32 2017
Thread Nº 2  Now sleeping after Lock acquired for  2
Thread Nº 2  Now releasing lock and sleeping again.
 Mon Jun 26 17:42:34 2017
Thread Nº 1  Now sleeping after Lock acquired for  2
Thread Nº 1  Now releasing lock and sleeping again.
 Mon Jun 26 17:42:36 2017
Thread Nº 2  Now sleeping after Lock acquired for  2
Thread Nº 2  Now releasing lock and sleeping again.
 Mon Jun 26 17:42:38 2017
Both threads exited, exiting.