Threading, real or simulated?
apardon at forel.vub.ac.be
Thu Sep 22 15:35:36 CEST 2005
Op 2005-09-22, Sam schreef <sam at email-scan.com>:
> Jp Calderone writes:
>> On Wed, 21 Sep 2005 18:23:33 -0500, Sam <sam at email-scan.com> wrote:
>>>I'm using Python 2.3.5 with pygtk 2.4.1, and I'm using the second threading
>>>approach from pygtk's FAQ 20.6 - invoking "gtk.gdk.threads_init()", and
>>>wrapping all gtk/gdk function calls with
>>>I start a thread, via thread.Threading.start(). The thread then calls a
>>>particularly time consuming C function, from an extension module. I find
>>>that when the thread is running the C code, the GUI hangs even though I'm
>>>not inside the threads_enter/threads_leave territory.
>> Does the extension module release the GIL? It sounds like it does not.
>> Of course, there are a dozen other mistakes that could be made which would
>> have roughly this symptom. It's difficult to say which is the problem
>> without actually seeing any code.
> What's the GIL?.
The general interpretor lock. In general changing python internals
is not thread-safe. The current implementation uses a lock (the GIL)
for thread to safely rebind variable or mutate object. The result
is that threads are serialised.
> The extension module is invoked outside of
>>>It looks like thread.Threading() only simulates threading, by having the
>>>python interpreter multiplex between running threads. Is real threading
>>>possible, so that I do something time-consuming in the thread, without
>>>hanging the GUI?
>> Assuming you mean threading.Thread, this is a native thread. It is not a simulation. Something else is going wrong.
> Then I must have something locked. Here's what I do:
Yes you have locked the GIL. Take a look at the following
URL: http://docs.python.org/api/threads.html, hope it helps.
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