Re: [U2] [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.

2011-10-26 Thread Mecki Foerthmann
You are right, you don't always know in advance which records you need to lock. If the processes are human controlled this can be solved by letting each user know who is locking whom out and they can solve the problem hopefully themselves. If phantom processes are doing this you don't have this

[U2] Avoiding deadly embraces (was Re: [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.)

2011-10-26 Thread asvin . dattani
Hi, You can avoid a deadly embrace if you can arrange it so that all processes lock related tables/files in the same sequence. Take the example of a system with a CUSTOMER file, a ORDER HEADER file and an ORDER DETAILS file. If some processes lock the ORDER HEADER file first and the CUSTOMER

Re: [U2] [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.

2011-10-26 Thread Robert Porter
Accountants... How about a ER doc waiting on lab results for cardiac enzymes? I can hear it now: Sorry Doc, something else locked the record. Your patient's test request was skipped so we could implement a trivial solution that was suggested for deadly embrace. Try again, and hope for the best

Re: [U2] UniBasic Question

2011-10-26 Thread Wols Lists
On 26/10/11 00:23, Steve Romanow wrote: I reread my post and meant no disrespect Wols. I shouldnt post replies without considering twice. No worries Steve. I shoot from the hip sometimes too - it can be embarrassing :-) Cheers, Wol ___ U2-Users

Re: [U2] Avoiding deadly embraces

2011-10-26 Thread David A. Green
I find the best practice is to try and lock and read all the necessary components before the first update. That way if an item we need to update as we go along is unavailable we catch it up front and don't get stuck. Or if you have TRANSACTION PROCESSING in place you can just to an ABORT. I

Re: [U2] Avoiding deadly embraces

2011-10-26 Thread Wjhonson
It's not possible to know every lock you may wish to set in advance David, that's the problem. Some locks can be set, but unknown, until the user has done something. Like in my example where the user changing a field in one record, causes another update to be triggered in some other record. You

Re: [U2] [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.

2011-10-26 Thread Mecki Foerthmann
Come on, get real. Do you suggest the deadly embrace would be better and he would get his results any quicker? And anyway, an ER doc not getting his lab results because of a mass update process running as a phantom encountering a locked record? And who would hold a lock on those lab results

Re: [U2] [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.

2011-10-26 Thread Robert Porter
I'm suggesting that blinding skipping records is a HORRIBLE idea, and in our case, potentially life threatening - literally. You need to get real with your suggestion that coding for deadly embrace situations is a very easy solution (your words). Not every phantom is a mass update. The IS

Re: [U2] Avoiding deadly embraces

2011-10-26 Thread Mecki Foerthmann
What do you think I am doing day in day out? I work with Avante 9.2 from Epicor and I definitely didn't write that myself. And this isn't the first system I've worked with in nearly 25 years in the MV world. And to be honest I have barely scratched the surface of Avante since I only look at

Re: [U2] Avoiding deadly embraces

2011-10-26 Thread Brian Leach
Will - you couldn't be more wrong in your last paragraph. FWIW Knowing Asvin and the systems he works on I can tell you they are anything but simple - highly complex rules handling many hundreds of concurrent processes and millions of transactions per day... in fact right at the other end of

Re: [U2] [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.

2011-10-26 Thread Mecki Foerthmann
I never said anything about blindly (I guess that's what you meant) skipping records. I suggested writing the locked record ids somewhere else and process them later for Wills not necessarily life-threatening sales rep update phantom. I at least don't feel threatened by accountants. If

Re: [U2] [UV] LIST.READU EVERY's waiters when there are writes w/o explicit readu.

2011-10-26 Thread Charles Stevenson
On 10/26/2011 7:45 AM, Robert Porter wrote: Accountants... How about a ER doc waiting on lab results for cardiac enzymes? I can hear it now: Sorry Doc, something else locked the record. Your patient's test request was skipped so we could implement a trivial solution that was suggested for

Re: [U2] Avoiding deadly embraces

2011-10-26 Thread Wjhonson
That's not really relevant to what I said. It's not a question at all of the *number* of transactions or processes, nor how complex the business rules are. It's much more relevant to the complexity of the history of the software. That someone would suggest that locks can be set in the same

Re: [U2] UniBasic Question

2011-10-26 Thread Dave Laansma
Oh, and Roadrunner is faster than Sonic ... definitely. :-) Sincerely, David Laansma IT Manager Hubbard Supply Co. Direct: 810-342-7143 Office: 810-234-8681 Fax: 810-234-6142 www.hubbardsupply.com Delivering Products, Services and Innovative Solutions -Original Message- From: