Python - Function is unable to run in new thread

问题:

I'm trying to kill the notepad.exe process on windows using this function:

import  thread, wmi, os
print 'CMD: Kill command called'
def kill():
    c = wmi.WMI ()
    Commands=['notepad.exe']

    if Commands[0]!='All':
        print 'CMD: Killing: ',Commands[0]
        for process in c.Win32_Process ():
          if process.Name==Commands[0]:
              process.Terminate()
    else:
        print 'CMD: trying to kill all processes'
        for process in c.Win32_Process ():
            if process.executablepath!=inspect.getfile(inspect.currentframe()):           
                try:
                    process.Terminate()
                except:
                    print 'CMD: Unable to kill: ',proc.name

kill() #Works               
thread.start_new_thread( kill, () ) #Not working

It works like a charm when I'm calling the function like this:

kill()

But when running the function in a new thread it crashes and I have no idea why.

回答1:

import  thread, wmi, os
import pythoncom
print 'CMD: Kill command called'
def kill():
    pythoncom.CoInitialize()
    . . .

Running Windows functions in threads can be tricky since it often involves COM objects. Using pythoncom.CoInitialize() usually allows you do it. Also, you may want to take a look at the threading library. It's much easier to deal with than thread.

回答2:

There are a couple of problems (EDIT: The second problem has been addressed since starting my answer, by "MikeHunter", so I will skip that):

Firstly, your program ends right after starting the thread, taking the thread with it. I will assume this is not a problem long-term because presumably this is going to be part of something bigger. To get around that, you can simulate something else keeping the program going by just adding a time.sleep() call at the end of the script with, say, 5 seconds as the sleep length.

This will allow the program to give us a useful error, which in your case is:

CMD: Kill command called
Unhandled exception in thread started by <function kill at 0x0223CF30>
Traceback (most recent call last):
  File "killnotepad.py", line 4, in kill
    c = wmi.WMI ()
  File "C:\Python27\lib\site-packages\wmi.py", line 1293, in connect
    raise x_wmi_uninitialised_thread ("WMI returned a syntax error: you're probably running inside a thread without first calling pythoncom.CoInitialize[Ex]")
wmi.x_wmi_uninitialised_thread: <x_wmi: WMI returned a syntax error: you're probably running inside a thread without first calling pythoncom.CoInitialize[Ex] (no underlying exception)>

As you can see, this reveals the real problem and leads us to the solution posted by MikeHunter.