Why the 'deadly embrace' issue
________________________________ From: Wjhonson <wjhon...@aol.com> To: u2-users@listserver.u2ug.org; sfr192...@yahoo.com Sent: Monday, October 24, 2011 8:42 PM Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o explicit readu. 20 points to anyone who is old enough to remember *why* we couldn't rely on the Locked clause. -----Original Message----- From: Charles Stevenson <stevenson.c...@gmail.com> To: Paul Wilson <sfr192...@yahoo.com>; U2 Users List <u2-users@listserver.u2ug.org> Sent: Mon, Oct 24, 2011 5:28 pm Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o explicit readu. Come to think of it, I think customizing CSC's MHC s/w was the 1st time I ever fought this fight. Before that, I had always programmed under a standard that demanded a READU before a WRITE. And every READU needed a LOCKED clause. cds On 10/24/2011 6:57 PM, Paul Wilson wrote: > That little company called CSC does/did not use readu's - they put login id > in field 1 and used that for a 'locking' situation. > > > > ________________________________ > From: "Woodward, Bob"<bob_woodw...@k2sports.com> > To: U2 Users List<u2-users@listserver.u2ug.org> > Sent: Monday, October 24, 2011 7:06 PM > Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o explicit readu. > > Oh I agree! I was just thinking round-robin that if we're going to talk > about adding a LOCKED clause to the WRITE statement, matching the > structure of READU, then we ought to have a WRITEU, too. Didn't say I > liked the idea.... > > -----Original Message----- > From: u2-users-boun...@listserver.u2ug.org > > [mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Mecki > Foerthmann > Sent: Monday, October 24, 2011 3:30 PM > To: u2-users@listserver.u2ug.org > Subject: Re: [U2] [UV] LIST.READU EVERY's > "waiters" when there are > writes w/o explicit readu. > > Now why would anybody want to use a WRITE without a READU? > I can possibly understand that somebody would want to do it with a > WRITEV (i.e writing a flag on a record) but WRITE? > And WRITE totally ignoring locking would be outright stupid. > > On 24/10/2011 22:28, Woodward, Bob wrote: >> I would think that because you are not trying to obtain the lock in a >> WRITE statement, it would not be classified as a waiter. True, it's >> waiting because of the lock but by not trying to obtain the lock, it's >> only waiting for the blockage to clear. If it were to be classified > as >> a waiter then I would expect to see a LOCKED clause on the WRITE >> statement like there is on the READU. For that matter, I'd expect to >> see a WRITEU command as well and the standard WRITE to completely > ignore >> locking. >> >> Just my guess, though. >> >> BobW >> >> -----Original Message----- >> From: u2-users-boun...@listserver.u2ug.org >> >> [mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles >> Stevenson >> Sent: Monday, October 24, 2011 2:12 PM >> To: U2 Users List >> Subject: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes >> w/o explicit readu. >> >> UV 10.2.10 on Windows is behaving differently from what I recall. >> Are my expectations out of line? >> >> Suppose Session A holds a readu lock; and Session B attempts a WRITE > to >> same record withOUT!!! 1st explicitly getting the readu lock. >> Session B waits for Session A to release the lock before writing the >> record. >> >> While Session B is waiting, does it show up as a "waiter" in > LIST.READU >> EVERY? >> I expected so, but it doesn't. >> >> >> Session A Session B >> _____________________________ ___________________ >> 1A. ED VOC DUMMY >> (this sets the readu lock.) >> >> 2A. (stay in editor) 2B. run this: >> 01: OPEN 'VOC' TO F ELSE > STOPM >> 'nope' >> 02: ***READU REC FROM F, 'DUMMY' >> ELSE NULL >> 03: WRITE '' TO F, 'DUMMY' >> >> 3A. Within ED: >> XEQ LIST.READU EVERY >> >> >> If I UN-comment line 2, LIST.READU EVERY shows something like this: >> >> Active Read Waiters: Owner Waiter >> Device.... Inode.... Userno Userno >> 746117947 232860913 6116 3396 >> >> >> But when I comment out line 2, LIST.READU is silent. >> I have not yet explored what the deadlock daemon does. >> >> TIA, >> cds >> >> >> P.S. Yes, yes, "Bad Form", "Legacy Software", 20 min wait is >> configurable, . . . we can talk later. _______________________________________________ U2-Users mailing list U2-Users@listserver.u2ug.org http://listserver.u2ug.org/mailman/listinfo/u2-users _______________________________________________ U2-Users mailing list U2-Users@listserver.u2ug.org http://listserver.u2ug.org/mailman/listinfo/u2-users
