Re: [WebDNA] Re: exclusivelock

This WebDNA talk-list message is from

2011

It keeps the original formatting. numero = 107020
interpreted = N
texte = Kenneth Grome wrote:> I'm saying I don't know how exclusivelock actually works,> and I don't know what issues we should (or must) keep in> mind when using it.>> Sincerely,> Kenneth GromeI have to admit that I didn't read this thread initially because itis a pet peeve of mine when people can't hit the "new message" button (instead of *replying* to someone's thread with their *new topic*)...So I don't know what was said already, but I think the docs spell it out pretty well, specifically it's intended purpose.Basically, as long as a lock can be acquired, the interior WebDNAwill be executed.. a test like this:----------------[Exclusivelock db=some.db][loop...]Searching (or other) that keeps some.db busy for a few minutes.[/loop][/Exclusivelock]Then in another browser, try to do something to some.db.----------------will result in the second hit waiting until the code within the exclusivelock is finished.----------------[loop...]Searching (or other) that keeps some.db busy for a few minutes.[/loop]Then in another browser, try to do something to some.db.----------------In the immediately above example, the hit in the second browser will not wait.As for deadlocks, I don't know the inner workings of WebDNA well enough off the top of my head to tell you exactly what goes on, but I seem to remember some mechanism to deal with deadlock possibilities native to the WebDNA database engine (separate from Exclusivelock).. butI could be wrong.For what it's worth, I started using Exclusivelock many years agofor situations such as described above... which is what the docs say it's purpose is for. However, I could see how using [Exclusivelock ..] would be an extra firewall against deadlocks as well... obviously, you can't have a deadlock if no other threads are accessing the file. ;-)Hope that helps.DonovanP.S. Please hit the "new message" button! ;-)-- Donovan BrookeEuca Design Center[Practical-Ethical-Efficient]www.euca.usegg.bzartglass-forum.com Associated Messages, from the most recent to the oldest:

[WebDNA] exclusivelock (Kenneth Grome 2011)

Kenneth Grome wrote:> I'm saying I don't know how exclusivelock actually works,> and I don't know what issues we should (or must) keep in> mind when using it.>> Sincerely,> Kenneth GromeI have to admit that I didn't read this thread initially because itis a pet peeve of mine when people can't hit the "new message" button (instead of *replying* to someone's thread with their *new topic*)...So I don't know what was said already, but I think the docs spell it out pretty well, specifically it's intended purpose.Basically, as long as a lock can be acquired, the interior WebDNAwill be executed.. a test like this:----------------[Exclusivelock db=some.db][loop...]Searching (or other) that keeps some.db busy for a few minutes.[/loop][/Exclusivelock]Then in another browser, try to do something to some.db.----------------will result in the second hit waiting until the code within the exclusivelock is finished.----------------[loop...]Searching (or other) that keeps some.db busy for a few minutes.[/loop]Then in another browser, try to do something to some.db.----------------In the immediately above example, the hit in the second browser will not wait.As for deadlocks, I don't know the inner workings of WebDNA well enough off the top of my head to tell you exactly what goes on, but I seem to remember some mechanism to deal with deadlock possibilities native to the WebDNA database engine (separate from Exclusivelock).. butI could be wrong.For what it's worth, I started using Exclusivelock many years agofor situations such as described above... which is what the docs say it's purpose is for. However, I could see how using [Exclusivelock ..] would be an extra firewall against deadlocks as well... obviously, you can't have a deadlock if no other threads are accessing the file. ;-)Hope that helps.DonovanP.S. Please hit the "new message" button! ;-)-- Donovan BrookeEuca Design Center[Practical-Ethical-Efficient]www.euca.usegg.bzartglass-forum.com Donovan Brooke

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