Date: Sat, 30 Aug 2003 15:05:48 -0400 (EDT) From: Garrett Wollman <wollman@khavrinen.lcs.mit.edu> To: Robert Watson <rwatson@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: Someone help me understand this...? Message-ID: <200308301905.h7UJ5msL042978@khavrinen.lcs.mit.edu> In-Reply-To: <Pine.NEB.3.96L.1030830121430.47993Q-100000@fledge.watson.org> References: <20030830160618.GA52499@stack.nl> <Pine.NEB.3.96L.1030830121430.47993Q-100000@fledge.watson.org>
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<<On Sat, 30 Aug 2003 12:23:35 -0400 (EDT), Robert Watson <rwatson@freebsd.org> said: > The only way to close this sort of race is to have a notion of a > unique process identifier that lasts beyond the lifetime of the > process itself -- i.e., the ability to return EMYSINCERESTREGRESTS > if you try to signal a process after it has died, and have a > guarantee that the handle won't be reused. This is traditionally done by holding an advisory lock on the pid file; if the file is no longer locked, then the process holding the lock must have exited. You could also do it with UUIDs and a more heavyweight signal API. -GAWollman
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