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[Pharo-project] Concurrent programming (was: Would you start a new Smalltalk project today?)
by Michael van der Gulik March 23, 2009

March 23, 2009

On Mon, Mar 23, 2009 at 12:18 AM, Igor Stasenko <siguctua(a)gmail.com> wrote: > 2009/3/22 Igor Stasenko <siguctua(a)gmail.com>: > > 2009/3/22 Michael van der Gulik <mikevdg(a)gmail.com>: > >> > >> > >> On Sat, Mar 21, 2009 at 8:38 AM, Janko MivÅ¡ek <janko.mivsek(a)eranova.si> > >> wrote: > >>> > >>> Philippe Marschall pravi: > >>> >> Michael van der Gulik wrote: > >>> > >>> >> So now it seems that Gemstone is the only multi-core capable > Smalltalk > >>> >> VM :-(. > >>> > >>> > AFAIK Gemstone isn't multi-core capable as well. You can just run > >>> > multiple gems and they share the same persistent memory. Which is > >>> > similar but different. > >>> > >>> Well, Gemstone can for sure be considered as multi-core capable. Every > >>> gem runs on its own process and therefore can run on its own CPU core. > >>> All gems then share a Shared Memory Cache. So, a typical multi-core > >>> scenario. > >>> > >> By multi-core, I mean that the following code would spread CPU usage > over at > >> least two cores of a CPU or computer for a while: > >> > >> | sum1 sum2 | > >> > >> sum1 := 0. sum2 := 0. > >> > >> [ 1 to: 10000000 do: [ :i | sum1 := sum1 + 1 ] ] fork. > >> > >> [ 1 to: 10000000 do: [ :i | sum2 := sum2 + 1 ] ] fork. > >> > >> (I didn't try the above so there might be obvious bugs) > >> > >> If a VM can't distribute the load for the above over two or more CPU > cores, > >> I consider its multi-core capabilities a hack. No offense intended to > the > >> Hydra VM. > >> > > > > Michael, that's would be too ideal to be true, especially for smalltalk. > > > > Consider the following: > > > > | array sum1 sum2 | > > > > sum1 := 0. sum2 := 0. > > array := Array new: 10. > > > > [ 1 to: 10000000 do: [ :i | array at: (10 random) put: (Array new: 10) ] > ] fork. > > [ 1 to: 10000000 do: [ :i | array at: (10 random) put: (Array new: 10) ] > ] fork. > > 1 to: 10000000 do: [ :i | array at: (10 random) put: (Array new: 10) ]. > > > > This code reveals the following problems: > > - concurrent access to same object > The problem here is that the code above wasn't written with concurrency in mind. I'd be looking at what I'm trying to acheive, and then try to keep each thread's data structures as disentangled as possible. If, for example, you were trying to allocate an array of arrays concurrently, then I would write (using my namespaces :-) ): array := Concurrent.Collections.Array new: 1000000000. " We ignore the cost of making this array to begin with :-) " array withIndexdo: [ :each :i | " each will always be nil. " array at: i put: (Array new: 10). ]. Concurrent.Collections.Array>>withIndexDo: aBlock | nThreads sema | nThreads := 1000. " Pull this from a system setting or something. " sema := Semaphore withSignals: 0-nThreads. " Needs implementing: signal it -1000 times. " 1 to: nThreads do: [ :i | [ (nThreads*i) to: (nThreads*i - 1) do: [ :j aBlock value: (self at: j) value: j ] ] fork ]. ^ self. There are probably bugs, I haven't tried running this. No synchronisation should be needed in this example, making it fast. Currently, this wouldn't work on the Squeak VM because block contexts aren't er... "reentrant". > > - a heavy memory allocation during running 3 processes, which at some > > point should cause GC. > > While first is more or less on the hands of developer (write a proper > > code to avoid such things), but second is a problem that you need to > > solve to be able to collect garbage in real time , when there are > > multiple threads producing it. > Then... invent a better garbage collector. This might be a difficult problem to solve, but it isn't impossible. http://gulik.pbwiki.com/Block-based+virtual+machine (ideas only) > > But what strikes me, that there are a lot of code, which never cares > about it, for instance see > Symbol class>> intern: > and in some magical fashion it works w/o problems in green threading.. > i'm not sure it will continue running when you enable multiple native > threads. I plan to find and fix these at some stage. Firstly, I would change the behaviour of the scheduler to get rid of the predictable yielding behaviour to expose these bugs. Doing so is required for the implementation of "Dominions" in my SecureSqueak project anyway, and I'll try to feed my changes back into the community. I also plan to make the Squeak equivalent of java.util.concurrent at some stage. > > > There is another problem, that squeak processes is cheap (few bytes in > object memory), while allocating new native thread consumes > considerable amount of memory & address space. So, if you map > Processes to native threads, you will lose the ability in having > millions of them, instead you will be limited to thousands. > Answered by Anthony which I agree with. Gulik. -- http://gulik.pbwiki.com/

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[Pharo-project] [ANN] Closures for beta testers
by StÃ©phane Ducasse March 23, 2009

March 23, 2009

Hi all I did the following: - loaded john adaptation layer - loaded install - followed the instructions - saved - load tempVariable fix - saved I did not saved the dirty packages for now. This release is to make sure that the image can be viable and that VM are working once we move to the closure. So can you check and let us know if this is working on the new VM 40 for the closures? Stef

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[Pharo-project] Software update
by Mariano Martinez Peck March 23, 2009

March 23, 2009

Hi guys. I am quite confused with software updates. When you do right button -> system -> software update, what is updated? just the core ? For example, tools like OB how must be updated ? Thanks, Mariano

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[Pharo-project] Site slow?
by Michael Rueger March 23, 2009

March 23, 2009

Hi all, the pharo site seems to be really slooow. Anyone else seeing this? Michael

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[Pharo-project] Mickael system submission Slice merging problem
by StÃ©phane Ducasse March 23, 2009

March 23, 2009

Hi mike could you redo you system organization changes? I checked with lukas we get a problem with the two merging tools :). Else what I can do is to keep track of the conflicts by hand (only a few) and load then revert. Because apparently MC does let me merge directly your changes. I can try to do the managing of your changes in late afternoon today. After I really want to work on the closures (but I have some important administration to do by tomorrow). Stef

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[Pharo-project] Issue 686: Remove dice methods in Random
by Serge Stinckwich March 23, 2009

March 23, 2009

http://code.google.com/p/pharo/issues/detail?id=686 -- Serge Stinckwich UMI UMMISCO 209 (IRD/UPMC), Hanoi, Vietnam Smalltalkers do: [:it | All with: Class, (And love: it)] http://doesnotunderstand.org/

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[Pharo-project] HowToContribute wiki page
by Serge Stinckwich March 23, 2009

March 23, 2009

Hi, i'm currently reading this page : http://code.google.com/p/pharo/wiki/HowToContribute and it's not really clear when someone do not need to make a modification to several packages ... I guess you have to publish to modified package to PharoInbox also. Best regards, -- Serge Stinckwich UMI UMMISCO 209 (IRD/UPMC), Hanoi, Vietnam Smalltalkers do: [:it | All with: Class, (And love: it)] http://doesnotunderstand.org/

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March 22, 2009

Begin forwarded message: > From: pharo-project-owner(a)lists.gforge.inria.fr > Date: March 19, 2009 3:13:47 PM CEST > To: ducasse(a)iam.unibe.ch > Subject: Issue 668: should clean the option-World click menu > > You are not allowed to post to this mailing list, and your message has > been automatically rejected. If you think that your messages are > being rejected in error, contact the mailing list owner at > pharo-project-owner(a)lists.gforge.inria.fr. > > > From: stÃ©phane ducasse <ducasse(a)iam.unibe.ch> > Date: March 19, 2009 3:13:40 PM CEST > To: Pharo Development <Pharo-project(a)lists.gforge.inria.fr> > Subject: Issue 668: should clean the option-World click menu > > > Issue 668: > should clean the option-World click menu > http://code.google.com/p/pharo/issues/detail?id=668 > Apparently option-click on the world brings a new menu (which points > to crappy stuff) and to the new pharo menu. >

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[Pharo-project] Pharo a VMs
by Mariano Martinez Peck March 22, 2009

March 22, 2009

Hi men! I know very little about VMs but I have a very simple question, which vms are 100% compatibles with Pharo ? I know standard vm, cog, exupery and hydra. And which of them that are compatible with pharo is the most "performant" ? thanks, Mariano

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[Pharo-project] Clock icon when vm is buzy
by Mariano Martinez Peck March 22, 2009

March 22, 2009

It would be nice to have a clock icon when the image is blocked doing something and then disappear when it finished. What I have to do, to get noticed when it terminates the block, is to click on another windows. So, when the vm returns control, then I goes to the windows I pick, and there I know. Is this possible to do? Cheers, Mariano

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