[libdispatch-dev] Fwd: Race in dispatch_semaphore_wait(DISPATCH_TIME_NOW)
sbn at tbricks.com
Thu May 22 02:09:33 PDT 2014
(forwarding to list)
On Wed, May 21, 2014 at 8:54 PM, Dave Zarzycki <zarzycki at apple.com> wrote:
> This is almost surely a bug in the port to these platforms. Apple’s
> operating system uses Mach to implement this feature, but Mach is not
> available on Linux and Solaris.
AFAIU libdispatch on OS X uses Mach semaphores instead of POSIX ones used
on Linux/Solaris. But the issue is irrelevant to OS semaphore
Actually I tried to reproduce it on OS X using (named) POSIX semaphores but
I.e. the same (racy) code that hangs on Linux/Solaris doesn't hang on OS X.
I even tried simple semaphore implementation using mutex+condition variable
but again no luck on OS X.
My guess is that this is related to differences in thread scheduler
implementations on these OS'es.
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