It is not possible to know in advance all the locks you may wish to set. That's the problem.
-----Original Message----- From: Charles Stevenson <[email protected]> To: U2 Users List <[email protected]> Sent: Tue, Oct 25, 2011 5:22 pm Subject: Re: [U2] [UV] LIST.READU EVERY's "waiters" when there are writes w/o explicit readu. While Will's articledoes give a good, clear example of a deadly embrace, nd remediating faulty code is not trivial, the solution is conceptually rivial and it is exactly the LOCKED clause that saves us. If you write new code, deadlocks are easy to prevent. Testing is non-trivial. It generally requires load or stress testing here mutiple processes vie for the same locks. In a nutshell: you shouldn't begin writing ANY part of a logical ransaction until you own ALL necessary locks. LOCKED clauses help you rap cases where you can't get one of those needed locks, allowing you o release all other related locks, (freeing up everything so the ompeting process can finish its work), then you try again. No eadlocks. QED. My problem posed at the start of this thread represents a conceptually rivial project but it will include retrofitting this anti-deadlock ogic. Non-trivial hours. Opportunity costs. More consistent data! All MV platforms support this same solution. If someone else wants to explain it in further detail for the newbies, lease, be my guest. cds On 10/25/2011 12:27 PM, Wjhonson wrote: This is deadly embrace http://knol.google.com/k/will-johnson/deadly-embrace-on-pick-systems/4hmquk6fx4gu/816#view The Locked clause does not save us from it. There is no known trivial olution to the problem, which troubles all multi-table, multi-user database nvironments. Perhaps we should start a new thread to discuss various approaches to the ssue. _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users ______________________________________________ 2-Users mailing list [email protected] ttp://listserver.u2ug.org/mailman/listinfo/u2-users _______________________________________________ U2-Users mailing list [email protected] http://listserver.u2ug.org/mailman/listinfo/u2-users
