[ECOS] FreeBSD stack / more threads, one socket

[ECOS] FreeBSD stack / more threads, one socket

[Richard Rauch]

Hi all,

we are using the FreeBSD stack and our application works with several
threads.
on one socket there are working 2 threads. the first is thread is waiting
for socket events with select( ), the second thread is calling send( ) and
receive( ).
is this allowed?
I'm asking, because when we have heavy communication load, then the stack
hangs (e.g no answers to ping) and we are searching for the reason

Thanks in advance

Richard



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Re: [ECOS] FreeBSD stack / more threads, one socket

[Nick Garnett]

"Richard Rauch" <Richard.Rauch@vipa.de> writes:

> Hi all,
> 
> we are using the FreeBSD stack and our application works with several
> threads.
> on one socket there are working 2 threads. the first is thread is waiting
> for socket events with select( ), the second thread is calling send( ) and
> receive( ).
> is this allowed?
> I'm asking, because when we have heavy communication load, then the stack
> hangs (e.g no answers to ping) and we are searching for the reason

I don't think that the BSD stack really expects you to be doing IO on
a socket that you are also selecting on. To start with, it would be
totally non-deterministic what happens when a packet arrives, does it
satisfy the recv() or the select(). Similarly with transmit, when the
buffers empty enough to allow a new transmission, does it satisfy the
select(), or release the send()?

I think you need to look more closely at your program, there seems to
be some confusion about what it want to do with this socket. I would
certainly never structure a program like this, on eCos, BSD or Linux.

Of course your problems may be unrelated, but I think this needs
fixing if only to eliminate it as a source of bugs.

-- 
Nick Garnett                    eCos Kernel Architect
http://www.ecoscentric.com/     The eCos and RedBoot experts


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