[Patches] [ python-Patches-452266 ] thread.kill_thread

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Patches item #452266, was opened at 2001-08-17 17:10
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Category: core (C code)
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Jason Petrone (jpetrone)
>Assigned to: Guido van Rossum (gvanrossum)
Summary: thread.kill_thread 

Initial Comment:
Function to unsafely kill a thread.  Implementations
are included for posix and nt.  If what I have looks
reasonable I will add other platforms + docs.

I've read Guido's usenet posts on this and 
understand the reasons against it, but I still think
it might be worth having.  Thread implementations 
like the ones in Java and win32 allow it with the
caveat that it could result in deadlock, 
corrupted data,  unclaimed resources, bodily harm, 
etc.  

Note that it also changes start_new_thread to return
the id for the new thread.


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>Comment By: Tim Peters (tim_one)
Date: 2001-08-19 14:24

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I've never called TerminateThread() on Win32, and given the 
dire wngs about it in the MS docs, never will.  IMO Python 
shouldn't be in this business unless it can guarantee to do 
it safely.  But it can't, so -1 from me.

Java did get out of this business:

<http://java.sun.com/products/jdk/1.2/docs/guide/misc/thread
PrimitiveDeprecation.html>

What Java has that Python lacks (follow the link) is a way 
to "interrupt" a thread, and there's nothing that was 
possible with thread.stop() that isn't possible by building 
on interruption (although the places where people really 
want this are places where thread.stop() never worked 
anyway -- Java never had a gimmick as Draconian as Win32's 
TerminateThread() -- Java's thread.stop() was "stop if you 
can, but there are many reasons you may not be able to").

I'd be +1 on a thread interruption facility for Python, 
which amounts to a way to raise an exception in a different 
thread.  But like Java's facility, it couldn't always 
guarantee the target thread would respond.

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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-08-18 23:27

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Assigned to Tim for review of the Windows code.

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Comment By: Guido van Rossum (gvanrossum)
Date: 2001-08-18 23:01

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I'm +0 with this, so it can go in if people really want it.
(Though isn't this deprecated in Java?) The patch looks very
thorough. Some concerns:

- Patches for Doc/lib/libthread.tex (don't have to be
perfect LaTeX, but must document new functionality).

- For other OS thread implementations (e.g. pth, solaris,
beos, os2) the thread ID returned by the thread module is
always zero.

- Some pthread implementations seem to have an issue that
the thread-id as we calculate it is not necessarily unique,
due to the opaqueness of the pthread_t structure.

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