On Oct 25, 2012, at 11:18 PM, Jacob Carlborg <d...@me.com> wrote: > On 2012-10-26 01:18, Sean Kelly wrote: >> On Oct 25, 2012, at 4:12 PM, Alex Rønne Petersen <a...@lycus.org> wrote: >>> >>> What's used on OS X? I forget... >> >> The method used is similar to how GC works on Windows--there's a kernel call >> that can be used to explicitly suspend a thread. I can't remember the >> function name offhand though. > > The Posix functions weren't working properly?
The semaphore implementation for OSX is not signal-safe. Originally, druntime used the signal approach on OSX and had deadlock issues in the signal handler (OSX semaphores wrap a global mutex to obtain something from a shared pool). Also, semaphores on OSX are just ridiculously slow. The current method for suspending and scanning threads on OSX is much faster. I wish Posix in general had the same feature. Using signals is really a hack. It may be worth dropping use of SIGUSR1/2 in favor of the realtime signals as well, since SIGUSR1/2 are in pretty common use.
