Is the standard output thread-safe?

[Fernando Rodríguez]

Hi,

Is the standard output thread-safe? Can I use print from several threads
without having to use a mutex?

Thanks

[danmcleran@yahoo.com]

Re: Is the standard output thread-safe?

>Is the standard output thread-safe?
No.

You'll need to synchronize access.

[Fredrik Lundh]

Re: Is the standard output thread-safe?

Fernando Rodríguez wrote:
[color=blue]
> Is the standard output thread-safe? Can I use print from several threads
> without having to use a mutex?[/color]

if you use sys.stdout.writ e on the standard sys.stdout stream, each write
operation is "atomic" (thanks to the GIL).

if you use other approaches (including print statements, or sys.stdout re-
direction via python code), data from different streams may appear out of
order. python won't crash, though.

</F>

[Fernando Rodríguez]

Re: Is the standard output thread-safe?

Hello Fredrik,
[color=blue]
> Fernando Rodríguez wrote:
>[color=green]
>> Is the standard output thread-safe? Can I use print from several
>> threads without having to use a mutex?
>>[/color]
> if you use sys.stdout.writ e on the standard sys.stdout stream, each
> write operation is "atomic" (thanks to the GIL).[/color]

GIL?

[Felipe Almeida Lessa]

Re: Is the standard output thread-safe?

Em Qui, 2006-03-09 às 16:37 +0000, Fernando RodrÃguez escreveu:[color=blue]
> Hello Fredrik,
>[color=green]
> > Fernando RodrÃguez wrote:
> >[color=darkred]
> >> Is the standard output thread-safe? Can I use print from several
> >> threads without having to use a mutex?
> >>[/color]
> > if you use sys.stdout.writ e on the standard sys.stdout stream, each
> > write operation is "atomic" (thanks to the GIL).[/color]
>
> GIL?
>[/color]

Global Interpreter Lock

--
"Quem excele em empregar a força militar subjulga os exércitos dos
outros povos sem travar batalha, toma cidades fortificadas dos outros
povos sem as atacar e destrói os estados dos outros povos sem lutas
prolongadas. Deve lutar sob o Céu com o propósito primordial da
'preservação' . Desse modo suas armas não se embotarão, e os ganhos
poderão ser preservados. Essa é a estratégia para planejar ofensivas."

-- Sun Tzu, em "A arte da guerra"

[Skull]

Re: Is the standard output thread-safe?

Fernando Rodríguez <frr@easyjob.ne t> writes:
[color=blue]
> Hi,
>
> Is the standard output thread-safe? Can I use print from several
> threads without having to use a mutex?
>
> Thanks
>
>[/color]

Check this: http://me.in-berlin.de/doc/python/fa...re-thread-safe

from my experience, it seems 'print' is not thread-safe. especially
when it is called with formated string, such as:

print "id:%d", my_id

I think it is not an "atomic" operation.

--