threads and extension module initialization

[pianomaestro@gmail.com]

I have an extension module that gets initialized multiple
times because I am using threads.

How can this module access global state (not per-thread state) ?
It needs to create a singleton.

Simon.

[Gabriel Genellina]

Re: threads and extension module initialization

En Fri, 28 Mar 2008 11:51:10 -0300, <pianomaestro@g mail.comescribi ó:

I have an extension module that gets initialized multiple
times because I am using threads.

And do you want thread local variables?

How can this module access global state (not per-thread state) ?
It needs to create a singleton.

C global variables are global, not per-thread.

--
Gabriel Genellina

[pianomaestro@gmail.com]

Re: threads and extension module initialization

On Mar 28, 11:14 am, "Gabriel Genellina" <gagsl-...@yahoo.com.a r>
wrote:

En Fri, 28 Mar 2008 11:51:10 -0300, <pianomaes...@g mail.comescribi ó:
>

I have an extension module that gets initialized multiple
times because I am using threads.

>
And do you want thread local variables?

no

>

How can this module access global state (not per-thread state) ?
It needs to create a singleton.

>
C global variables are global, not per-thread.

Yes, but they get initialized once per-thread, therefore my singleton
gets
created multiple times.

Simon.

>
--
Gabriel Genellina

[pianomaestro@gmail.com]

Re: threads and extension module initialization

On Mar 28, 11:14 am, "Gabriel Genellina" <gagsl-...@yahoo.com.a r>
wrote:

C global variables are global, not per-thread.

aha, a static pointer gets initialized to NULL, so I
can check if it's not NULL in the module initializer.

Thanks for jogging my brain,

Simon.

>
--
Gabriel Genellina

[Gabriel Genellina]

Re: threads and extension module initialization

En Fri, 28 Mar 2008 12:25:55 -0300, <pianomaestro@g mail.comescribi ó:

On Mar 28, 11:14 am, "Gabriel Genellina" <gagsl-...@yahoo.com.a r>
wrote:

>En Fri, 28 Mar 2008 11:51:10 -0300, <pianomaes...@g mail.comescribi ó:
>>

How can this module access global state (not per-thread state) ?
It needs to create a singleton.

>>
>C global variables are global, not per-thread.

>
Yes, but they get initialized once per-thread, therefore my singleton
gets
created multiple times.

Either don't call the initialization from every thread, or guard it with
something like:

a_big_object my_object = NULL;
....

if (my_object!=NUL L) {
...initialize object...
my_object = ...;
}

That's a pretty standard idiom I think.

--
Gabriel Genellina

[Diez B. Roggisch]

Re: threads and extension module initialization

pianomaestro@gm ail.com schrieb:

I have an extension module that gets initialized multiple
times because I am using threads.
>
How can this module access global state (not per-thread state) ?
It needs to create a singleton.

The question is very unclear.

If you are after *not* initializing your module concurrently, why don't
you just do it *once* before the threads are started? alternatively, you
need to govern the initialization-code with a mutex - or anything similar.

Diez

[Gabriel Genellina]

Re: threads and extension module initialization

En Fri, 28 Mar 2008 13:17:44 -0300, Diez B. Roggisch <deets@nospam.w eb.de>
escribió:

pianomaestro@gm ail.com schrieb:

>I have an extension module that gets initialized multiple
>times because I am using threads.
>>
>How can this module access global state (not per-thread state) ?
>It needs to create a singleton.

>
The question is very unclear.
>
If you are after *not* initializing your module concurrently, why don't
you just do it *once* before the threads are started? alternatively, you
need to govern the initialization-code with a mutex - or anything
similar.

Ouch... The simple "if (foo!=NULL)" I posted earlier is not thread safe
and should not be used in this situation. Do as Diez said.

--
Gabriel Genellina