From owner-freebsd-hackers Fri Aug 27 19:46:59 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from allegro.lemis.com (allegro.lemis.com [192.109.197.134]) by hub.freebsd.org (Postfix) with ESMTP id 5445A15492 for ; Fri, 27 Aug 1999 19:46:53 -0700 (PDT) (envelope-from grog@freebie.lemis.com) Received: from freebie.lemis.com (freebie.lemis.com [192.109.197.137]) by allegro.lemis.com (8.9.1/8.9.0) with ESMTP id MAA18104; Sat, 28 Aug 1999 12:16:59 +0930 (CST) Received: (from grog@localhost) by freebie.lemis.com (8.9.3/8.9.0) id MAA14395; Sat, 28 Aug 1999 12:16:55 +0930 (CST) Date: Sat, 28 Aug 1999 12:16:54 +0930 From: Greg Lehey To: Christian Kuhtz Cc: Thomas David Rivers , bee@wipinfo.soft.net, hackers@FreeBSD.ORG Subject: Re: Mandatory locking? Message-ID: <19990828121654.D13904@freebie.lemis.com> References: <000301beeea6$1ea898a0$88291fac@wipro.tcpn.com> <199908251005.GAA95394@lakes.dignus.com> <19990826090933.T83273@freebie.lemis.com> <19990825195322.D4723@ns1.adsu.bellsouth.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.95.4i In-Reply-To: <19990825195322.D4723@ns1.adsu.bellsouth.com>; from Christian Kuhtz on Wed, Aug 25, 1999 at 07:53:22PM -0400 WWW-Home-Page: http://www.lemis.com/~grog X-PGP-Fingerprint: 6B 7B C3 8C 61 CD 54 AF 13 24 52 F8 6D A4 95 EF Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Wednesday, 25 August 1999 at 19:53:22 -0400, Christian Kuhtz wrote: > On Thu, Aug 26, 1999 at 09:09:33AM +0930, Greg Lehey wrote: >> On Wednesday, 25 August 1999 at 6:05:11 -0400, Thomas David Rivers wrote: >>>> All the files under Tandem's NSK has mandatory locking. The file cannot be >>>> opened if another process has it opened. some thing like >>>> >>>> * if the file is opened for reading, any one can open it for >>>> reading but opening for writing gives error >>>> * if the file is open for writing, it can't be opened for >>>> read/write >>>> * if the process holding the file is killed, the lock is gone >>>> * it is possible to get the pid of the process(es) which has >>>> a given file open (like which process has file "xyz" open? >>>> kind of query). btw, is there any way to get this info now in FBSD? >>> >>> This sounds interesting... >>> >>> But - aren't there NFS issues? I mean, in stateless access to >>> a file - how do you know if the process holding the file is killed >>> if it's remote? >> >> NSK is a prorietary operating system ("NonStop Kernel", previously >> known as Guardian, previously known as TOS), not UNIX. There is no >> NFS, and there is no distinction between network access and local >> access: all goes over the message system. When a file is closed, its >> locks are released. > > How does this message system handle releasing stale locks when components > talking to the message system die unexpectedly? Is there some sort of aging, > override or timeout mechanism to purge stale locks? When a process dies unexpectedly, the message system releases all resources which were allocated to it. This includes, of course, closing its files. If the process is on the local processor, the locak processor cleans up. If the local processor dies, the remote systems are informed and do the cleanup for all resources used by processes on that processor. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message