Date: Sun, 5 Feb 2012 14:29:43 -0500 (EST) From: Daniel Eischen <deischen@freebsd.org> To: Jilles Tjoelker <jilles@stack.nl> Cc: Garrett Cooper <yanegomi@gmail.com>, freebsd-hackers@freebsd.org, Ivan Voras <ivoras@freebsd.org>, Xin LI <delphij@delphij.net>, Jan Mikkelsen <janm-freebsd-hackers@transactionware.com>, davidxu@freebsd.org Subject: Re: sem(4) lockup in python? Message-ID: <Pine.GSO.4.64.1202051428390.28760@sea.ntplx.net> In-Reply-To: <20120205190022.GC57421@stack.nl> References: <jejrbe$or8$1@dough.gmane.org> <201201110806.30620.jhb@freebsd.org> <CAF-QHFWFvYTPeM68Mk%2BOYVX--MNhKOJ2o1GF9ZOsBmtiC5fYFQ@mail.gmail.com> <CAGH67wRsek2-WY_ETW6QEER1r5dDXLXfDjbzpHMjtv059Y8cJw@mail.gmail.com> <5D37298B-9D68-4F0F-8AAB-E8F2DBB9D9C3@transactionware.com> <CAGH67wT3HuxPHUXeTib0qJNH%2BO5snn3Eiim1bfj8LewYoKdXdA@mail.gmail.com> <CAF-QHFVADLkduLH1AG_hSZeDtDVCC=FkqZxbxrsMY3Y3%2BsMZ8A@mail.gmail.com> <Pine.GSO.4.64.1202051330020.28531@sea.ntplx.net> <20120205190022.GC57421@stack.nl>
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This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---559023410-851401618-1328470183=:28760 Content-Type: TEXT/PLAIN; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE On Sun, 5 Feb 2012, Jilles Tjoelker wrote: > On Sun, Feb 05, 2012 at 01:32:42PM -0500, Daniel Eischen wrote: >> On Sun, 5 Feb 2012, Ivan Voras wrote: >>> On 5 February 2012 11:44, Garrett Cooper <yanegomi@gmail.com> wrote: > >>>> =A0 =A0'make MAKE_JOBS_NUMBER=3D1' is the workground used right now.. > >>> David Xu suggested that it is a bug in Python - it doesn't set >>> process-shared attribute when it calls sem_init(), but i've tried >>> patching it (replacing the port patchfile file the one I've attached) >>> and I still get the hang. > >> I don't understand how process shared semaphores can work. Perhaps >> I'm dumb and ignorant, but a sem_id_t is an allocated struct. The >> actual kernel sem_id is inside the struct. Isn't this the same >> reason pthread_mutex_t and pthread_cond_t cannot be process-shared? > > That's how the old implementation works. It does not support > process-shared semaphores although they may happen to work in some > specific cases. > > However, in 9.0, sem_t works differently and contains the actual lock > word directly, so that process-shared semaphores work. The > implementation is in lib/libc/gen/sem_new.c. The pshared flag to > sem_init() is not a no-op because it tells the kernel to allow for use > from multiple processes. > > Note that the old implementation is still present as well, for > compatibility with old binaries. Ahh, okay, I was looking at the old implementation in libc. --=20 DE ---559023410-851401618-1328470183=:28760--
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