Re: [gentoo-user] Is my system (really) using nptl

[Mark Knecht <markknecht@gmail.com>]

On Sat, Oct 13, 2012 at 11:16 AM, Canek Peláez Valdés <caneko@gmail.com> wrote:
> On Sat, Oct 13, 2012 at 12:10 PM, Mark Knecht <markknecht@gmail.com> wrote:
>> On Sat, Oct 13, 2012 at 9:15 AM, Canek Peláez Valdés <caneko@gmail.com> wrote:
>> <SNIP>
>>>
>>> We can only know seeing the code. Timur, this is the little test I
>>> made which creates 5 threads and runs them for 1 minute. In my case,
>>> `ps x` shows only 1 PID, care to give it a try?
>>>
>>> ----------------------
>>> #include <pthread.h> <<======
>>> #include <unistd.h>
>>> #include <stdlib.h>
>>> #include <stdio.h>
>>
>> Thanks for the test case. Like you I see only one thread. However the
>> test case wouldn't compile for me without the -pthread option so it
>> makes me wonder what happens to a program like I had pointed to
>> yesterday that uses the old style threading that did create lots of
>> process ids? Possibly an nptl system would still generate lots of ids
>> for that program and that's what he's seeing?
>>
>> Just curious. I don't program but I'm always sort of interested.
>
> You got your answer. NTPL stands for Native POSIX Thread *Library*. As
> it name says, it is a library (with support in the kernel and in
> glibc). If you don't use the library (-lpthread), you cannot make use
> of its advantages.
>
> What "old style threading" did you use for your test case?
>
> Regards.
> --
> Canek Peláez Valdés
> Posgrado en Ciencia e Ingeniería de la Computación
> Universidad Nacional Autónoma de México
>

As for 'old style' I only meant code that did threads but didn't use
the POSIX libraries. (I guess...)

Actually I hadn't run the test case at the time but was referring to
the one I pointed the OP at yesterday:

http://www.makelinux.net/alp/032

However it's essentially the same as yours (not as elegant, but
functionally similar). However the results shown on that page show
different pids for the threads. When I run that same code here I get
the same pids:

mark@c2stable ~ $ ./pthread2
main thread pid is 5387
child thread pid is 5387
^C
mark@c2stable ~ $

Now, this does make me curious about some things running on my system.
Two for instance, Google Chrome and akonadi_agent, have LOTS of pids.
I was assuming those were different threads and were demonstrating
what the OP was asking about, but now I'm not so sure. How does a
single program on an nptl system generate all these different pids?

Thanks,
Mark