Re: How to kill threading.Thread instance?
On 2008-09-21, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > Diez B. Roggisch wrote: > >>> I wonder why something like myThread.exit() or myThread.quit() or >>> threading.kill(myThread) can't be implemented? >>> Is something like that present in Python 3000? >> >> Not that I'm aware of it (which doesn't mean to much though). >> >> However I *am* aware of the bazillions discussions that have been held >> over this here - and the short answer is: it is a generally very bad >> idea to terminate threads hard, as it can cause all kinds of corruption. > > the problem is that you have no idea what the thread is doing, so just > killing it dead it may make one big mess out of the application's > internal state; see e.g. this post > >http://mail.python.org/pipermail/python-list/2006-August/400256.html > >That's wise ;-) Stopping a thread asynchronously is in /general/ a >dangerous thing to do, and for obvious reasons. For example, perhaps >the victim thread is running in a library routine at the time the >asynch exception is raised, and getting forcibly ejected from the >normal control flow leaves a library-internal mutex locked forever. >Or perhaps a catch-all "finally:" clause in the library manages to >release the mutex, but leaves the internals in an inconsistent state. > > which links to a FAQ from Sun on this very topic: > > http://java.sun.com/j2se/1.3/docs/guide/misc/threadPrimitiveDeprecation.html > > (note that Java releases all mutexes when a thread is killed, but that's > not much better, as the FAQ explains) > > so as usual, the right thing to do is to do things in the right way. Why not let the programmer make the call whether killing the thread dead is the right thing or not. Maybe the programmer has a pretty good idea about what the thread can possibilbly be doing and knows that killing it won't produce a mess. Sure caution people to be very carefull when they are thinking about doing something like this. Just as people are generally adviced to use Queues when doing multithreading. But that is no reason to disallow certain kind of actions. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: How to kill threading.Thread instance?
On Sep 21, 4:04 pm, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > Diez B. Roggisch wrote: > >> I wonder why something like myThread.exit() or myThread.quit() or > >> threading.kill(myThread) can't be implemented? > >> Is something like that present in Python 3000? > > > Not that I'm aware of it (which doesn't mean to much though). > > > However I *am* aware of the bazillions discussions that have been held > > over this here - and the short answer is: it is a generally very bad > > idea to terminate threads hard, as it can cause all kinds of corruption. > > the problem is that you have no idea what the thread is doing, so just > killing it dead it may make one big mess out of the application's > internal state; see e.g. this post > > http://mail.python.org/pipermail/python-list/2006-August/400256.html > > That's wise ;-) Stopping a thread asynchronously is in /general/ a > dangerous thing to do, and for obvious reasons. For example, perhaps > the victim thread is running in a library routine at the time the > asynch exception is raised, and getting forcibly ejected from the > normal control flow leaves a library-internal mutex locked forever. > Or perhaps a catch-all "finally:" clause in the library manages to > release the mutex, but leaves the internals in an inconsistent state. > > which links to a FAQ from Sun on this very topic: > > http://java.sun.com/j2se/1.3/docs/guide/misc/threadPrimitiveDeprecati... > > (note that Java releases all mutexes when a thread is killed, but that's > not much better, as the FAQ explains) > > so as usual, the right thing to do is to do things in the right way. > > Often you know terminated a thread would be perfectly safe - and not being able to is very frustrating - particularly if your calculation is coarse grained and there is no convenient point to regularly poll for a stop signal. .NET solves the 'you might interrupt important stuff' by guaranteeing that an asynchronous ThreadAbortException won't be raised inside a finally block. Michael http://www.ironpythoninaction.com/ -- http://mail.python.org/mailman/listinfo/python-list
Re: How to kill threading.Thread instance?
Diez B. Roggisch wrote: I wonder why something like myThread.exit() or myThread.quit() or threading.kill(myThread) can't be implemented? Is something like that present in Python 3000? Not that I'm aware of it (which doesn't mean to much though). However I *am* aware of the bazillions discussions that have been held over this here - and the short answer is: it is a generally very bad idea to terminate threads hard, as it can cause all kinds of corruption. the problem is that you have no idea what the thread is doing, so just killing it dead it may make one big mess out of the application's internal state; see e.g. this post http://mail.python.org/pipermail/python-list/2006-August/400256.html That's wise ;-) Stopping a thread asynchronously is in /general/ a dangerous thing to do, and for obvious reasons. For example, perhaps the victim thread is running in a library routine at the time the asynch exception is raised, and getting forcibly ejected from the normal control flow leaves a library-internal mutex locked forever. Or perhaps a catch-all "finally:" clause in the library manages to release the mutex, but leaves the internals in an inconsistent state. which links to a FAQ from Sun on this very topic: http://java.sun.com/j2se/1.3/docs/guide/misc/threadPrimitiveDeprecation.html (note that Java releases all mutexes when a thread is killed, but that's not much better, as the FAQ explains) so as usual, the right thing to do is to do things in the right way. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to kill threading.Thread instance?
dmitrey schrieb: I wonder why something like myThread.exit() or myThread.quit() or threading.kill(myThread) can't be implemented? Is something like that present in Python 3000? Not that I'm aware of it (which doesn't mean to much though). However I *am* aware of the bazillions discussions that have been held over this here - and the short answer is: it is a generally very bad idea to terminate threads hard, as it can cause all kinds of corruption. Systems like Java discourage the use of the available methods for that as well. And I for example once worked with Qt3-threads, what allow for this kind of operation - and killed my CORBA-ORB running in the same process by terminating the thread hard. Google a bit in this NG to find the discussions & reasons. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: How to kill threading.Thread instance?
I wonder why something like myThread.exit() or myThread.quit() or threading.kill(myThread) can't be implemented? Is something like that present in Python 3000? Regards, D. -- http://mail.python.org/mailman/listinfo/python-list
Re: How to kill threading.Thread instance?
dmitrey wrote: BTW, it should be noticed that lots of threading module methods have no docstrings (in my Python 2.5), for example _Thread__bootstrap, _Thread__stop. things named _Class__name are explicitly marked private by the implementation (using the "__" prefix). using them just because you can find them via "dir" is a really stupid idea. (and, as noted in the comment section to the recipe, the "stop" method flags a thread as stopped, it doesn't stop it.) -- http://mail.python.org/mailman/listinfo/python-list
Re: How to kill threading.Thread instance?
dmitrey schrieb: hi all, Is there a better way to kill threading.Thread (running) instance than this one http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/496960 (it's all I have found via google). Nope. There might be other ways technically, but none of them falls into a "better"-classification. Diez -- http://mail.python.org/mailman/listinfo/python-list
