Threading and Windows.

[Brian Kelley]

Re: Threading and Windows.

If you are using wxPython you might want to check out this little package:

http://staffa.wi.mit.edu/people/kelley/

look for LongRunningTask s at the bottom.

-brian

[Jorge Godoy]

Re: Threading and Windows.

Dennis Lee Bieber <wlfraed@ix.net com.com> writes:
[color=blue]
> Jorge Godoy fed this fish to the penguins on Tuesday 30 September 2003
> 09:01 am:
>[color=green]
>>
>> The most interesting thing is that I get an error in Windows but I
>> don't get such an error in Linux.
>>[/color]
> spawnv() is probably a direct match with a unix/linux system call, so
> the arguments are just being passed on -- and what linux does when it
> gets the address of a string where it expected an integer constant is
> unknown to me (probably sees the address /as/ the integer, and since
> P_WAIT is 0, the runtime is treating any non-zero to be the equivalent
> of P_NOWAIT)[/color]

The behaviour of treating it as nonzero would be expected. What
happens is the opposite of that as I described before: the program
hangs as if it received P_WAIT.


I think that they check explicitly for P_NOWAIT and treat anything
different as zero (P_WAIT).


The principle of least surprise was violated, IMVHO as a newbie on
that area. :-)


See you,
--
Godoy. <godoy@metalab. unc.edu>

[Jorge Godoy]

Re: Threading and Windows.

Brian Kelley <bkelley@wi.mit .edu> writes:
[color=blue]
> If you are using wxPython you might want to check out this little package:
>
> http://staffa.wi.mit.edu/people/kelley/
>
> look for LongRunningTask s at the bottom.
>
> -brian[/color]

I didn't knew this address but I got something like that from

http://wiki.wxpython.org/index.cgi/LongRunningTasks

It didn't solve my problem but thanks for this new pointer.

In my case I really needed something that ran a new proccess.

--
Godoy. <godoy@metalab. unc.edu>

[Dennis Lee Bieber]

Re: Threading and Windows.

Dennis Lee Bieber fed this fish to the penguins on Tuesday 30 September
2003 10:17 am:

[color=blue][color=green]
>>[/color]
> spawnv() is probably a direct match with a unix/linux system[/color]

Okay, I took some time at work to look at the source for os.py... My
assumptions are totally backwards...

From my email to myself:

Had a reversal... spawnv() does not exit on Linux, which uses
combination of (see os.py for actual code):

pid = fork()
if not pid: #new process
execv() #replace with desired program
else:
if mode == P_NOWAIT:
return pid
while 1: # why the loop?
status = waitpid(pid, 0)
#tests for status return


Since 'P_NOWAIT' is not equal to os.P_NOWAIT, Linux defaults to
performing the wait operation.

It is on Windows where a low-level _spawnv() exists,
int _spawnv( int mode, const char *cmdname, const char *const *argv );
and the error is raised when Python tries to convert the string
'P_NOWAIT' into the integer mode for the direct call.

--[color=blue]
> =============== =============== =============== =============== == <
> wlfraed@ix.netc om.com | Wulfraed Dennis Lee Bieber KD6MOG <
> wulfraed@dm.net | Bestiaria Support Staff <
> =============== =============== =============== =============== == <
> Bestiaria Home Page: http://www.beastie.dm.net/ <
> Home Page: http://www.dm.net/~wulfraed/ <[/color]

[Bengt Richter]

Re: [SOLVED] Re: Threading and Windows.

On Tue, 30 Sep 2003 10:54:57 -0300, Jorge Godoy <godoy@metalab. unc.edu> wrote:
[color=blue]
>Dennis Lee Bieber <wlfraed@ix.net com.com> writes:
>[color=green]
>> Jorge Godoy fed this fish to the penguins on Monday 29 September 2003
>> 07:31 pm:
>>[color=darkred]
>>>
>>> This isn't the behaviour I found here on a Linux box. The caller
>>> process got 'stuck' and only worked again when the called proccess
>>> ended.
>>>[/color]
>> Strange...[/color]
>
>OK... I tracked it down and found the 'P_NOWAIT' didn't work. I
>replaced it with '1' (no quotes) and everything went fine on bot OSs.
>[/color]
What is os.P_NOWAIT on your system? It looks like '1' (no quotes) on my system:
[color=blue][color=green][color=darkred]
>>> import os
>>> os.name[/color][/color][/color]
'nt'[color=blue][color=green][color=darkred]
>>> os.P_NOWAIT[/color][/color][/color]
1
[color=blue]
>The error message on Windows helped finding it out (it said that an
>integer was expected but I got nothing on Linux).
>[color=green]
>> You might have to explicitly invoke the python executable, and pass
>> /it/ the .py file as the first argument[/color]
>
>It ended up like this:
>
> os.spawnv(1, 'c:/python22/pythonw.exe', ['c:/python22/pythonw.exe', 'another.py', parameter])[/color]
So one would think

os.spawnv(os.P_ NOWAIT, 'c:/python22/pythonw.exe',
['c:/python22/pythonw.exe', 'another.py', parameter])

would work, except I note that os.P_NOWAIT is not defined in Python 1.5.2 on Linux (slackware).
Gotta upgrade one of these days... My nt python is 2.3 though, but I don't suppose that's changed
since the 2.2 you are apparently running on windows??

Regards,
Bengt Richter

[Jorge Godoy]

Re: [SOLVED] Re: Threading and Windows.

bokr@oz.net (Bengt Richter) writes:
[color=blue][color=green]
>>OK... I tracked it down and found the 'P_NOWAIT' didn't work. I
>>replaced it with '1' (no quotes) and everything went fine on bot OSs.
>>[/color]
> What is os.P_NOWAIT on your system? It looks like '1' (no quotes) on my system:
>[color=green][color=darkred]
> >>> import os
> >>> os.name[/color][/color]
> 'nt'[color=green][color=darkred]
> >>> os.P_NOWAIT[/color][/color]
> 1[/color]

It is '1', just as in yours. I was saying that there's no 'P_NOWAIT'
(with quotes and no 'os.' prefix). :-)
[color=blue]
> So one would think
>
> os.spawnv(os.P_ NOWAIT, 'c:/python22/pythonw.exe',
> ['c:/python22/pythonw.exe', 'another.py', parameter])[/color]

Exactly. In fact it ended up as (this is in a separate method on the
main program):

if (sys.platform == 'win32'):
python = 'c:/python22/pythonw.exe'
os.spawnv(os.P_ NOWAIT, python, [python, program, parameter])
else:
os.spawnv(os.P_ NOWAIT, program, [program, parameter])
[color=blue]
> would work, except I note that os.P_NOWAIT is not defined in Python 1.5.2 on Linux (slackware).
> Gotta upgrade one of these days... My nt python is 2.3 though, but I don't suppose that's changed
> since the 2.2 you are apparently running on windows??[/color]

I'm running 2.2 on both platforms and with the 'os.' prefix everything
worked. :-)


Thanks,
--
Godoy. <godoy@metalab. unc.edu>

[Tim Evans]

Re: [SOLVED] Re: Threading and Windows.

Jorge Godoy <godoy@metalab. unc.edu> writes:[color=blue]
> [snip]...it ended up as (this is in a separate method on the main
> program):
>
> if (sys.platform == 'win32'):
> python = 'c:/python22/pythonw.exe'
> os.spawnv(os.P_ NOWAIT, python, [python, program, parameter])
> else:
> os.spawnv(os.P_ NOWAIT, program, [program, parameter])[/color]

You should probably just be using this on both systems:

os.spawnv(os.P_ NOWAIT, sys.executable, [sys.executable, program, parameter])

--
Tim Evans

[Jorge Godoy]

Re: [SOLVED] Re: Threading and Windows.

Tim Evans <t.evans@paradi se.net.nz> writes:
[color=blue]
> Jorge Godoy <godoy@metalab. unc.edu> writes:[color=green]
>> [snip]...it ended up as (this is in a separate method on the main
>> program):
>>
>> if (sys.platform == 'win32'):
>> python = 'c:/python22/pythonw.exe'
>> os.spawnv(os.P_ NOWAIT, python, [python, program, parameter])
>> else:
>> os.spawnv(os.P_ NOWAIT, program, [program, parameter])[/color]
>
> You should probably just be using this on both systems:
>
> os.spawnv(os.P_ NOWAIT, sys.executable, [sys.executable, program, parameter])[/color]

VERY interesting.

I think that with that I can avoid checkin the OS the software will be
running in.

Thanks.


See you,
--
Godoy. <godoy@metalab. unc.edu>