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Re: [Pharo-project] [squeak-dev] Re: Xtreams port to Squeak - second wave

by mkobetic＠gmail.com

"Levente Uzonyi"<leves(a)elte.hu> wrote: > Okay, I really tracked down the cause of the problem. The tests perform > simple producer-consumer scenarios, but the consumers won't wait at all. > If there's nothing to consume, the test fails. The randomness come from > the scheduler. The server process is started first, the client is the > second. If the server process can produce enough input to the client > process the test will pass. > If you decrease the priority of the client process by one in > #timeout:server:client:, the randomness will be gone and the tests will > reliably pass, because the client won't be able to starve the server. To > avoid false timeouts I had to increase the timeout value to 2000 > milliseconds using SqueakVM. An alternative solution I was thinking about would be to dispense with the processes in default case and simply run the server and client blocks sequentially. The cases where we really need the processes are channels with limited capacity (e.g. Socket or Pipe) where the writer needs to be able to block (when the OS buffers fill up) and let the reader consume some of the output before it continues writing. In these cases there aren't any shared resources so process contention should not be an issue. The other advantage would be that cases with the default behavior would be easier to debug and would not be subject to timeouts. As it is I still get timeouts sporadically even when it's set to 1 second. > I also found an issue: the process in XTTransformWriteStream doesn't > terminate. If you run the tests, you'll get 12 lingering processes. I don't see that happening in Pharo 1.1. Normally the process should end normally when the stream is closed (the close synchronizes with the process via the closeReady semaphore). Maybe there's a missing close somewhere in the test suite ?

Oct. 12, 2010

Re: [Pharo-project] [squeak-dev] How about atomic value-swap bytecode?

by Igor Stasenko

On 12 October 2010 17:07, Lukas Renggli <renggli(a)gmail.com> wrote: >> To swap two values, you usually do: >> >> | var1 var2 temp | >> >> temp := var1. >> var1 := var2. >> var2 := temp. >> >> But since its non-atomic, a process can be interrupted and such operation >> is not thread-safe. > > As far as I know the VM only preempts on back-jumps and message sends. > None of that exists in your code snipped, so it should be atomic. No? > This is a bit blurry. I remember Eliot said it is no longer true under Cog VM. > Lukas > > -- > Lukas Renggli > www.lukas-renggli.ch > > _______________________________________________ > Pharo-project mailing list > Pharo-project(a)lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > -- Best regards, Igor Stasenko AKA sig.

Oct. 12, 2010

Re: [Pharo-project] [squeak-dev] How about atomic value-swap bytecode?

by Lukas Renggli

> To swap two values, you usually do: > > | var1 var2 temp | > > temp := var1. > var1 := var2. > var2 := temp. > > But since its non-atomic, a process can be interrupted and such operation > is not thread-safe. As far as I know the VM only preempts on back-jumps and message sends. None of that exists in your code snipped, so it should be atomic. No? Lukas -- Lukas Renggli www.lukas-renggli.ch

Oct. 12, 2010

Re: [Pharo-project] [squeak-dev] Re: How about atomic value-swap bytecode?

by Igor Stasenko

On 12 October 2010 16:51, Levente Uzonyi <leves(a)elte.hu> wrote: > On Tue, 12 Oct 2010, Igor Stasenko wrote: > >> Hello, i just thought, that it would be cool to have a special bytecode, >> which guarantees atomicity for swapping values between two variables. >> >> To swap two values, you usually do: >> >> | var1 var2 temp | >> >> temp := var1. >> var1 := var2. >> var2 := temp. >> >> But since its non-atomic, a process can be interrupted and such operation >> is not thread-safe. >> >> In order to make it thread safe, you must add even more boilerplate: >> >> | var1 var2 temp | >> >> semaphore critical: [ >> Â temp := var1. >> Â var1 := var2. >> Â var2 := temp. >> ] > > An alternative solution: > > | a b | > a := 1. > b := 2. > [ > Â Â Â Â | tmp | > Â Â Â Â tmp := a. > Â Â Â Â a := b. > Â Â Â Â b := tmp ] valueUnpreemptively > Yeah, another boilerplate under the hood, also highly dependent from scheduling nuances :) valueUnpreemptively "Evaluate the receiver (block), without the possibility of preemption by higher priority processes. Use this facility VERY sparingly!" "Think about using Block>>valueUninterruptably first, and think about using Semaphore>>critical: before that, and think about redesigning your application even before that! After you've done all that thinking, go right ahead and use it..." | activeProcess oldPriority result | activeProcess := Processor activeProcess. oldPriority := activeProcess priority. activeProcess priority: Processor highestPriority. result := self ensure: [activeProcess priority: oldPriority]. "Yield after restoring priority to give the preempted processes a chance to run" Processor yield. ^result > > Levente > -- Best regards, Igor Stasenko AKA sig.

Oct. 12, 2010

Re: [Pharo-project] How about atomic value-swap bytecode?

by Levente Uzonyi

On Tue, 12 Oct 2010, Igor Stasenko wrote: > Hello, i just thought, that it would be cool to have a special bytecode, > which guarantees atomicity for swapping values between two variables. > > To swap two values, you usually do: > > | var1 var2 temp | > > temp := var1. > var1 := var2. > var2 := temp. > > But since its non-atomic, a process can be interrupted and such operation > is not thread-safe. > > In order to make it thread safe, you must add even more boilerplate: > > | var1 var2 temp | > > semaphore critical: [ > temp := var1. > var1 := var2. > var2 := temp. > ] An alternative solution: | a b | a := 1. b := 2. [ | tmp | tmp := a. a := b. b := tmp ] valueUnpreemptively Levente > > So, i thought , if we could have a special bytecode, then we could > write something like: > > | var1 var2 | > > var1 :=: var2. > > So, VM will guarantee that values of var1 and var2 will be swapped > atomically, and completely thread-safe. > > var1 and var2 could be either temps or instance variables, but of > course not arguments, since they are not assignable. > > One thing i don't like, that it will need to introduce a new syntax > for atomic-value-swap operator - :=: > > Or, maybe just reserve a special keyword selector (which is recognized > by compiler), so > > var1 __atomicSwapWith: var2 > > so it will look like a regular smalltalk syntax, except that its not a > message send, but a low-level operation instead. > > > -- > Best regards, > Igor Stasenko AKA sig. > > _______________________________________________ > Pharo-project mailing list > Pharo-project(a)lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project >

Oct. 12, 2010

Re: [Pharo-project] Learning by download all the mcz files from a repository

by HwaJong Oh

Hi, Alex. sorry for late reply i've been busy could not have time to review Ecco. I have a small question, I can find Ecco is treating 'Seaside' package special than other ones. Does it have some purpose? Have a good one HwaJong Oh -- View this message in context: http://forum.world.st/Learning-by-download-all-the-mcz-files-from-a-reposit… Sent from the Pharo Smalltalk mailing list archive at Nabble.com.

Oct. 12, 2010

Re: [Pharo-project] FreeType and finalization

by Igor Stasenko

I can modify Freetype to not use subclass of weakregistry, and still guarantee non-duplication. Is Freetype a separate maintained package, or its part of Pharo core? On 12 October 2010 16:25, Gary Chambers <gazzaguru2(a)btinternet.com> wrote: > Indeed... never seen that error hence proposal for simplest solution. > > Regards, Gary > > ----- Original Message ----- From: "Igor Stasenko" <siguctua(a)gmail.com> > To: <Pharo-project(a)lists.gforge.inria.fr> > Sent: Tuesday, October 12, 2010 1:21 PM > Subject: Re: [Pharo-project] FreeType and finalization > > >> 2010/10/12 Gary Chambers <gazzaguru2(a)btinternet.com>: >>> >>> Hi all, I've encountered a problem with FreeType with respect to the new >>> finalization scheme. >>> http://code.google.com/p/pharo/issues/detail?id=3096 >>> Regards, Gary >>> >> >> FT2HandleRegistry overrides following method: >> >> add: anObject >> "Add anObject to the receiver. Store the object as well as the >> associated executor." >> | executor dup | >> executor := anObject executor. >> dup := nil. >> self protected:[ >> dup := valueDictionary detect: [ :v | v handle = executor handle ] >> ifNone: [ ]. >> valueDictionary at: anObject put: executor. >> ]. >> dup ifNotNil: [ self error: 'Duplicate object added!'. self remove: >> anObject ]. >> ^anObject >> >> >> As i see, the intent is to prevent registering a same handle twice, >> so in own turn, when time will come, a #finalize won't attempt to >> destroy same handle twice. >> >> The proposed fix (as you wrote in issue tracker) >> >> registry >> ^Registry ifNil: [ Registry := WeakRegistry new] >> >> appears to fix the problem... >> >> But apparently its not the same as in original. >> Okay, but since we never seen Â the error: 'Duplicate object added!', >> then i think it may work without it :) >> >> Still, it would be good to know, how handles are created, and what the >> chances that they could be duplicated. >> >> -- >> Best regards, >> Igor Stasenko AKA sig. >> >> _______________________________________________ >> Pharo-project mailing list >> Pharo-project(a)lists.gforge.inria.fr >> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > > > _______________________________________________ > Pharo-project mailing list > Pharo-project(a)lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project > -- Best regards, Igor Stasenko AKA sig.

Oct. 12, 2010

Re: [Pharo-project] FreeType and finalization

by Gary Chambers

Indeed... never seen that error hence proposal for simplest solution. Regards, Gary ----- Original Message ----- From: "Igor Stasenko" <siguctua(a)gmail.com> To: <Pharo-project(a)lists.gforge.inria.fr> Sent: Tuesday, October 12, 2010 1:21 PM Subject: Re: [Pharo-project] FreeType and finalization > 2010/10/12 Gary Chambers <gazzaguru2(a)btinternet.com>: >> Hi all, I've encountered a problem with FreeType with respect to the new >> finalization scheme. >> http://code.google.com/p/pharo/issues/detail?id=3096 >> Regards, Gary >> > > FT2HandleRegistry overrides following method: > > add: anObject > "Add anObject to the receiver. Store the object as well as the > associated executor." > | executor dup | > executor := anObject executor. > dup := nil. > self protected:[ > dup := valueDictionary detect: [ :v | v handle = executor handle ] > ifNone: [ ]. > valueDictionary at: anObject put: executor. > ]. > dup ifNotNil: [ self error: 'Duplicate object added!'. self remove: > anObject ]. > ^anObject > > > As i see, the intent is to prevent registering a same handle twice, > so in own turn, when time will come, a #finalize won't attempt to > destroy same handle twice. > > The proposed fix (as you wrote in issue tracker) > > registry > ^Registry ifNil: [ Registry := WeakRegistry new] > > appears to fix the problem... > > But apparently its not the same as in original. > Okay, but since we never seen the error: 'Duplicate object added!', > then i think it may work without it :) > > Still, it would be good to know, how handles are created, and what the > chances that they could be duplicated. > > -- > Best regards, > Igor Stasenko AKA sig. > > _______________________________________________ > Pharo-project mailing list > Pharo-project(a)lists.gforge.inria.fr > http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project

Oct. 12, 2010

[Pharo-project] How about atomic value-swap bytecode?

by Igor Stasenko

Hello, i just thought, that it would be cool to have a special bytecode, which guarantees atomicity for swapping values between two variables. To swap two values, you usually do: | var1 var2 temp | temp := var1. var1 := var2. var2 := temp. But since its non-atomic, a process can be interrupted and such operation is not thread-safe. In order to make it thread safe, you must add even more boilerplate: | var1 var2 temp | semaphore critical: [ temp := var1. var1 := var2. var2 := temp. ] So, i thought , if we could have a special bytecode, then we could write something like: | var1 var2 | var1 :=: var2. So, VM will guarantee that values of var1 and var2 will be swapped atomically, and completely thread-safe. var1 and var2 could be either temps or instance variables, but of course not arguments, since they are not assignable. One thing i don't like, that it will need to introduce a new syntax for atomic-value-swap operator - :=: Or, maybe just reserve a special keyword selector (which is recognized by compiler), so var1 __atomicSwapWith: var2 so it will look like a regular smalltalk syntax, except that its not a message send, but a low-level operation instead. -- Best regards, Igor Stasenko AKA sig.

Oct. 12, 2010

Re: [Pharo-project] Adding a new font in System like DejaVu fonts

by Juan Vuletich

Henrik Johansen wrote: > > On Oct 10, 2010, at 12:49 40PM, nullPointer wrote: > >> >> Now I know is possible add a new font, for use cross platform like >> DejaVu. I >> know Juan Vuletich did that but I donÂ´t know found the place of that is >> explained. Is heard do that? > > Whuups, might've sent you in a wild goose chase, sorry :/ > > Was thinking > of http://forum.world.st/DemoMode-should-not-change-Fonts-only-sizes-td2538706… , > which I interpreted as linking to a description of how he builds the > font source. > Clearly that only includes the end result ready for import. > > Anyways, as can be seen from the AAFonts.zip, you basically need a bmp > with the font glyphs, as well as a text file containing offsets for > each character. > You could achieve that through printscreen and manual creation of > offsets txt, or using a more automated tool similar to f.ex. > http://www.angelcode.com/products/bmfont/ . > > CC'ing Juan in case he has time to comment on what his process is > specifically. I just used a few Smalltalk scripts that find glyph boundaries using the various pixel tally methods. Cheers, Juan Vuletich >> takes very space of image when the font is >> added? > > About as much space as the bmp's, ie depends on what sizes you want to > include. > > Cheers, > Henry >

Oct. 12, 2010