at-exit-thread

[castironpi at gmail.com]

On Feb 29, 2:12 pm, castiro... at gmail.com wrote:
> On Feb 29, 1:55 pm, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
>
>
>
>
>
> > castiro... at gmail.com schrieb:
>
> > > The Python main interpreter has an at-exit list of callables, which
> > > are called when the interpreter exits.  Can threads have one?  What's
> > > involved, or is the best way merely to subclass Thread?
>
> > Is that some sort of trick-question?
>
> > class MyThread(Thread):
>
> >     def run(self):
> >         while some_condition:
> >              do_something()
> >         do_something_after_the_thread_ends()
>
> > The atexit stuff is for process-termination which is/may be induced by
> > external signals - which is the reason why these callbacks extist.
> > Threads don't have that, thus no need.
>
> That depends.  If a thread adds an object it creates to a nonlocal
> collection, such as a class-static set, does it have to maintain a
> list of all such objects, just to get the right ones destroyed on
> completion?  Processes destroy their garbage hassle-free; how can
> threads?  And don't forget Thread.run( self ) in the example, if
> anyone ever wants to make use of the 'target' keyword.- Hide quoted text -

Two snippets from the docs that are worrisome:

# If they invoke anything in threading.py that calls currentThread(),
they
# leave an entry in the _active dict forever after.
-threading.py

thread.get_ident()
... Thread identifiers may be recycled when a thread exits and another
thread is created.
-thread module doc

If you try to look up something by thread_id, you can get a terminated
thread's old resources.  at-thread-exit could prevent it.  What is the
scope of a resource a daemon thread allocates?