How to kill a thread?

Diez B. Roggisch deets at
Fri Jun 6 18:21:17 CEST 2008

Laszlo Nagy schrieb:
>>         def run(self):
>>                 while True:
>>                         if exit_event.isSet():
>>                                 # Thread exiting
>>                                 return
>>                         try:
>>                                 data = q_in.get(timeout = .5)
>>                         except Queue.Empty:
>>                                 continue
>>                         # ... process data
>> And then in the MainThread I do exit_event.set() and wait for all 
>> threads to exit. It's a pretty awkward solution but works.
>> BTW Guys, is something like Thread.kill() planned for the future? Or 
>> is there a reason not to have it?
> Python threads are cooperative. I think there was a discussion about 
> this, about a year ago or so. The answer was that in CPython, the 
> interpreter has this GIL. Python threads are always running on the same 
> processor, but they are not "native". There are operating system 
> functions to kill a thread but you must not use them because it can 
> crash the interpreter. 

This is not correct. Neither are threads cooperative nor are they not 
native. If they weren't cooperative they needed explicit re-scheduling 
statements in the code. And they also are based on native OS threads.

They might *appear* not cooperative if a long-running C-call doesn't 
release the GIL beforehand.

This of course doesn't affect other parts of your reasoning about 
killing threads being a bad idea and such.


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