Date: Tue, 19 Nov 2002 00:01:20 -0500 (EST) From: Garrett Wollman <wollman@lcs.mit.edu> To: "Brian Smith" <dbsoft@technologist.com> Cc: "current@freebsd.org" <current@FreeBSD.ORG> Subject: Re: Are SysV semaphores thread-safe on CURRENT? Message-ID: <200211190501.gAJ51KFZ019862@khavrinen.lcs.mit.edu> In-Reply-To: <20021119043130.WWGB397.mail1-0.chcgil.ameritech.net@bbs> References: <Pine.GSO.4.10.10211182130110.12758-100000@pcnet1.pcnet.com> <20021119043130.WWGB397.mail1-0.chcgil.ameritech.net@bbs>
next in thread | previous in thread | raw e-mail | index | archive | help
<<On Mon, 18 Nov 2002 22:31:28 -0600, "Brian Smith" <dbsoft@technologist.com> said: > Is this the recommended method of preventing these problems? The recommended method of preventing these problems generally is to use POSIX semaphores (or other POSIX synchronization mechanisms appropriate to threaded programs. However, the code to implement process-shared POSIX semaphores is still experimental. The problem with System V semaphores is that there is no way to poll their status while still polling the process's file descriptors. This could be fixed by introducing a new kqueue filter, but the semantics of System V semaphores are difficult to emulate. Depending on the semantics you require, a semaphore may be implemented using a pipe or fifo, or by using file or record locking. -GAWollman To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200211190501.gAJ51KFZ019862>