Date: Thu, 24 Dec 2009 07:59:47 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-threads@freebsd.org Cc: threads@freebsd.org, David Xu <davidxu@freebsd.org> Subject: Re: first patch for process-shared semaphore Message-ID: <200912240759.47703.jhb@freebsd.org> In-Reply-To: <20091223221219.4416cef6@kan.dnsalias.net> References: <4B317741.8080004@freebsd.org> <4B32CADA.4010407@freebsd.org> <20091223221219.4416cef6@kan.dnsalias.net>
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On Wednesday 23 December 2009 10:12:19 pm Alexander Kabaev wrote: > On Thu, 24 Dec 2009 09:58:50 +0800 > David Xu <davidxu@freebsd.org> wrote: > > > Alexander Kabaev wrote: > > > On Thu, 24 Dec 2009 09:22:34 +0800 > > > David Xu <davidxu@freebsd.org> wrote: > > >> libthr does not require semaphore, it implements semaphore, > > >> it is easier than other ways to implement the process-shared. > > >> > > > Let me rephrase: I do not think semaphores belong in libthr. They > > > should be either in libc or in librt. > > > > > > > > OK, does others really implement semaphore in librt ? > > unfortunately, the librt already requires libpthread to implement > > SIGEV_THREAD. > > I retract that. It appears that there is no consistency - Solaris put > these into libc, Linux into libpthread ans SUSv2 hints that these > belong with realtime functions. libthr is fine. I vote for libc. Single-threaded processes can use sem_open() and PSHARED sem_init() as well. Single-threaded processes can even use non-PSHARED sem_init() by using fork() to create new "threads" that share the semaphore. -- John Baldwin
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