Starting a thread before wxPython bootup ... interesting.

On 10/4/07, Shafik <sh******@gmail.comwrote:

Hello folks,

I'm having an issue with mixing wxPython and threading ... I realize
multi-threading always introduces subtle bugs, but the following
scenario is just odd:

I start a dummy thread, that does nothing but increment a counter and
print its value to the screen, then afterwards, I start the wxPython
application. I get nothing but weird behavior: sometimes the gui just
crashes, sometimes I get an exception, sometimes it runs for a little
but very slowly ...

Anyone know whats going on? I have a dual-core T5500, so multi
threading is piece of cake for it hardware -wise.

That's quite a broad and poorly specified problem to ask people to
solve with no code. You get double minus points for mentioning an
exception without saying what it was.

Below is a script that has no demonstrable problems on my machine:

import wx
import threading

if __name__ == '__main__':
run = True
def count():
counter = 0
while run:
print counter
counter += 1
thread = threading.Thread(target=count)
thread.start()
app = wx.App(False)
f = wx.Frame(None)
f.Show()
app.MainLoop()
run = False

Since the counter loop spins tightly, this causes some CPU contention
and could quite possibly cause a non-trivial GUI to respond poorly,
but that's to be expected.

Since the observed behaviour is clearly undefined,
I forgive you for the poorly specified behaviour
description: asking for a close description of random
behaviour is just ridiculous.

The most obvious point is that wx is not re-entrant
or thread safe: you have to make it so by using
wx.CallAfter()

Since you are talking about a bug in your screen
display while using a screen library, it would
also be interesting it you described the environment:
Which operating system? Which windowing system?
Which wx library? Which Python? Which IDE? What code?

[david]


Shafik wrote:

Hello folks,

I'm having an issue with mixing wxPython and threading ... I realize
multi-threading always introduces subtle bugs, but the following
scenario is just odd:

I start a dummy thread, that does nothing but increment a counter and
print its value to the screen, then afterwards, I start the wxPython
application. I get nothing but weird behavior: sometimes the gui just
crashes, sometimes I get an exception, sometimes it runs for a little
but very slowly ...

Anyone know whats going on? I have a dual-core T5500, so multi
threading is piece of cake for it hardware -wise.
Cheers,
--Shafik

>

The real goal is to start the gui in a different thread, and have the
main thread regain control. That seems like a feasible thing to be
able to do, though I have been unsuccessful ... if anyone would like
to suggest something without being covertly insulting, I'm all ears.

AFAIK some toolkits take it personally if they don't run in THE thread,
meaning the main-thread. No idea if that applies to your situation, but
as you continue to being vague, so are the answers.

Diez