Re: [Newbies] BlockClosurefork problem
George, You'll find that writing to the Transcript always slows things down. I assume it's the time for writing to the Transcript that also causes the second process to start after a different interval each time. Writing the results into an OrderedCollection will be much faster, and more predictable: a := OrderedCollection new. [10 timesRepeat: [a addLast: '2'. (Delay forMilliseconds: 1) wait]] fork. [10 timesRepeat: [a addLast: '1'. (Delay forMilliseconds: 1) wait]] fork. a inspect. consistently gives 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1. Without the delay: a := OrderedCollection new. [10 timesRepeat: [a addLast: '2']] fork. [10 timesRepeat: [a addLast: '1']] fork. a inspect. consistently gives 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1. Cheers, Michael ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Process Scheduling (was Re: BlockClosurefork problem)
On Feb 20, 2007, at 11:05 , Michael Davies wrote: George, You'll find that writing to the Transcript always slows things down. I assume it's the time for writing to the Transcript that also causes the second process to start after a different interval each time. Besides, it interferes with processes because it has a Mutex nowadays. Which is good, but it distorts what you would observe without the Transcript involved. Writing the results into an OrderedCollection will be much faster, and more predictable: a := OrderedCollection new. [10 timesRepeat: [a addLast: '2'. (Delay forMilliseconds: 1) wait]] fork. [10 timesRepeat: [a addLast: '1'. (Delay forMilliseconds: 1) wait]] fork. a inspect. consistently gives 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1. This is because waiting on Delay (or, rather on the Semaphore inside) causes the current process to block, and the next process on the same priority to run. The same could be achieved by Processor yield instead of waiting on the Delay. This is cooperative. Or, you could have a higher-priority scheduler that time-slices the lower-priority ones by suspending them in turn, which does not need cooperation. Without the delay: a := OrderedCollection new. [10 timesRepeat: [a addLast: '2']] fork. [10 timesRepeat: [a addLast: '1']] fork. a inspect. consistently gives 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1. These processes are too short-lived to ever get interrupted by a higher priority process. So the first one runs to completion, then the second one. Try this instead: a := String new writeStream. p1 := [[a nextPut: $1] repeat] forkAt: Processor userBackgroundPriority. p2 := [[a nextPut: $2] repeat] forkAt: Processor userBackgroundPriority. 10 timesRepeat: [(Delay forMilliseconds: 1) wait]. p1 terminate. p2 terminate. a contents This puts the two processes into a lower priority than the UI process. We then stop the UI process 10 times for one millisecond - this is our scheduler. Each time, the next lower-priority process is given time to run - that is the default scheduling behavior. The result are nicely alternating runs of ones and twos as you would expect: '112221222...' - Bert - ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
[Newbies] Creating custom events in a domain.
Hi Squeakers, I am working an a project where we have a domain. this domain should not know the classes outside the world, so to communicate the domain should fire an event where the classes outside the domain could react to. How could this be done? I didn't find anything about it in the wiki.. Kind regards, Mispunt ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] Creating custom events in a domain.
Il giorno mar, 20/02/2007 alle 12.43 +0100, Mispunt ha scritto: Hi Squeakers, I am working an a project where we have a domain. this domain should not know the classes outside the world, so to communicate the domain should fire an event where the classes outside the domain could react to. How could this be done? I didn't find anything about it in the wiki.. Hi Mispunt, you may try using the Announcements framework. Lukas Renggli recently blogged about it at http://www.lukas-renggli.ch/blog/decoupling Ciao, Giovanni ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] BlockClosurefork problem
Thanks for this answer, Ron. But actually I'm not confused with order in wich '1' and '2' presents in result line. I can't understand why in some cases this code results ten '1' and ten '2' and in some cases it results ten '2' and only nine '1'? ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
Re: [Newbies] BlockClosurefork problem
Thanks, Michael! Now I know, that it isn't a problem of BlockClosure's fork method, but a specific behaviour of Transcript. Code you give in your message result the same line as VW. George ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
RE: [Newbies] BlockClosurefork problem
George, Oh I'm really sorry. It's funny now that I go back and look I'm surprised that I missed that. That's a horse of a different color. Basically to answer your question Transcript is not thread safe. I'm not sure exactly where it goes wrong but I suspect that it is probably doing a copy somewhere and if one collection is used as a source and is copied at the same time with two new additions then one gets lost. To fix that you can set a semaphore which basically says don't try to access Transcript from two places at exactly the same time. semaphore := Monitor new. [10 timesRepeat: [semaphore critical: [Transcript show: '2']]] fork. [10 timesRepeat: [semaphore critical: [Transcript show: '1']]] fork. Transcript cr. This should make transcript thread safe. Hope that helps, Ron Teitelbaum -Original Message- From: [EMAIL PROTECTED] [mailto:beginners- [EMAIL PROTECTED] On Behalf Of George Herolyants Sent: Tuesday, February 20, 2007 3:28 PM To: A friendly place to get answers to even the most basic questions aboutSqueak. Subject: Re: [Newbies] BlockClosurefork problem Thanks for this answer, Ron. But actually I'm not confused with order in wich '1' and '2' presents in result line. I can't understand why in some cases this code results ten '1' and ten '2' and in some cases it results ten '2' and only nine '1'? ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners ___ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
