线程错误：AttributeError: 'NoneType' 对象没有属性 '_initialized'

Question

我正在尝试了解 Python 3 上的线程。我制作了一个示例代码：

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 时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。

我能做些什么来纠正这个问题？

谢谢你们！

Answer 1

您使用的Thread完全不正确。首先，你不调用Thread构造函数（即你的代码必须具有threading.Thread(<something>)创建新Thread实例）。其次，您myfunction在主线程中调用with 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参数传递给未绑定的Thread.start方法！

正确的做法是

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

同样对于t2. 此外，如果你像这样做，你将保留引用Thread对象，并且可以更换while 1: pass用

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

或者同样：

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

通过这些修改，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.