Le 7 déc. 05 à 02:00, Lee Revell a écrit :
On Wed, 2005-11-02 at 11:48 +0100, Florian Schmidt wrote:
On Wed, 2 Nov 2005 11:05:34 +0100
Stéphane Letz <[EMAIL PROTECTED]> wrote:
In Jackdmp we have tested 2 system for inter-process
synchronization:
fifo (the way it was done in regular jackd) and POSIX named
semaphore
(which are built on top of futex on recent system version)
In both cases, each already running client get access to the
synchronization primitive (fifo or POSIX named sema) defined by a
new
coming client. The synchronization primitive is "opened" once when a
new client appears and is "closed" when the client quits. The
synchronization primitive that has to be signaled then depends of
the
graph topology.
But ISTR that OSX only has named shared futexes (i.e. accessed
via a file descriptor), and then of course the problem remains.
On OSX, on can use Mach semaphore (internal and non portable...)
POSIX named semaphore or fifo.
Stephane
What results did you get? Did the semaphore perform better/worse than
the fifo? What about pthread condition variables with pshared flag
set?
I read somewhere it should be implemented by now (at least on 2.6
systems).
I've tested process shared mutexes/CVs with NPTL 2.3.5 on Linux 2.6
and
it works perfectly - I'm able to synchronize multiple processes via a
mutex/CV residing in shared memory, backed by an mmap'ed file in /tmp.
Do you have any test code you could share?
The performance is indistinguishable from the single multithreaded
process case.
Is there any good reason JACK could not use this rather than FIFOs?
Lack of robustness?
jackd (of jackdmp in "synch" mode) where the server waits for all
clients to finish in a given cycle require the used synchronization
primitive to have a "wait with time-out" operation. Fifo can do that
(using poll), Mach semaphore on OSX can do that, but POSIX named
semaphore not.
Do process shared mutexes/CVs have a "wait with time-out" operation.?
Thanks
Stephane
