Squeak-dev May 2009

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102 participants
131 discussions

A fun issue with Debugger
by Igor Stasenko 03 May '09

03 May '09

Open a workspace, type: 1 then open menu and pick debug-it. You wont be able to do anything else until press the interrupt key. It applies to both 3.10.2. and Pharo with closures. -- Best regards, Igor Stasenko AKA sig.

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Improving a Process termination procedure
by Igor Stasenko 02 May '09

02 May '09

There are a potential of having incorrect behavior , when terminating a preempted or waiting process: with introduction of ProcessLocalVariable, it is essential that context unwinding procedure should be performed only for currently active process. Here the proposal how to ensure this: if terminating process is not active process we should do the following: suspendedContext := proc suspendedContext. currentProces := Processor activeProcess. proc suspendedContext: [ Processor activeProcess terminateFromContext: suspendedContext. Processor switchToProcess: currentProcess ] asContext. Processor switchToProcess: proc. here #switchToProcess: is explicit switch (bypassing scheduling logic). If we don't care about immediate termination of process and getting back to process who initiated termination as soon as possible, then simply do: process terminateSoon. which can be implemented as: Process>>terminateSoon | termContext | termContext := suspendedContext. suspendedContext := [ self terminateFromContext: termContext. self suspend ] asContext. Processor yield. -- Best regards, Igor Stasenko AKA sig.

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Help with ImageSegments
by Brent Pinkney 02 May '09

02 May '09

Hi, I would like to use image segments in 3.9. I need to export a tree of objects to a file and then load the segment into a different image. Thanks -- Brent

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[Update] New scheduler (Was: [ANN] A new scheduler + VM changes alpha-release)
by Igor Stasenko 02 May '09

02 May '09

A new version is available on Mantis: http://bugs.squeak.org/view.php?id=7345 - added an image boot sequence. Now its cleverly picks an appropriate scheduler depending on VM. - a process termination is rewritten, - added a TerminateProcess exception , which could be used to perform additional actions during process termination [ .... ] on: TerminateProcess do: [:ex | .... ] - a process which is being terminated runs as active process. This is to ensure, that any #ensure: / #on:do: / #ifCurtailed: blocks will run in same environment as during normal execution. Please evaluate :) 2009/5/1 Igor Stasenko <siguctua(a)gmail.com>: > 2009/5/1 Andreas Raab <andreas.raab(a)gmx.de>: >> Igor Stasenko wrote: >>> >>> I have built a new VM with closure support (VMMaker.dtl.120). >>> A changeset can be loaded to VMMaker w/o changes, except changing the >>> Interpreter class redefinition. >>> All is needed is to add 3 class vars to Interpreter manually: >>> ProcessActionIndex InterruptedProcessIndex InterruptProcessIndex >> >> Hm ... I compiled a VM with your changes but I can't recreate your results. >> My results are more in the range of 15:1 to 20:1 in a before-after >> comparison. Are you using the code from >> http://bugs.squeak.org/view.php?id=7345 or something more elaborate by now? >> > Well, i made some shortcuts, like removing fallback handler and it > improved a bit. > I checked everything thoughoutly, and since performance degrades > linearly with each introduced message send, > i don't think its because of bogus code. > The overhead is because we using interpreter to switch processes: > -removing process from a list > - adding process to a list > etc etc. > > Of course, i could make an additional prims to speed things up for a > little, like doing > LinkedList>>removeFirst: > LinkedList>>addLast: > primitively. > But i wouldn't care about it now. I want to explore the real benefits > of having scheduling logic at language side - like reimplementing > Delays, adding nicer process termination procedure (see my other > thread) etc. > >> Cheers, >> - Andreas >> >> > > > > -- > Best regards, > Igor Stasenko AKA sig. > -- Best regards, Igor Stasenko AKA sig.

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Setting a preempted process priority glitch
by Igor Stasenko 02 May '09

02 May '09

Here the test, showing that setting a priority of preempted process may not result of what you expected: | first p1 p2 | first := nil. p1 := [ first ifNil: [ first:= 1] ] forkAt: Processor activePriority - 1. p2 := [ first ifNil: [ first:= 2] ] forkAt: Processor activePriority - 2. p1 priority: 10. (Delay forMilliseconds: 100) wait. first at first, an order in which processes should awake is p1 then p2. But then, if we setting p1 priority lower than p2 , the order should be p2 then p1. To fix this we should reschedule preempted process: Process>>priority: anInteger (anInteger >= Processor lowestPriority and:[anInteger <= Processor highestPriority]) ifTrue: [priority := anInteger] ifFalse: [self error: 'Invalid priority: ', anInteger printString] (myList isNil or: [myList class == Semaphore]) ifTrue: [ ^ self ]. "we are preempted. reschedule at new priority" self suspend;resume. This issue shows, that comment in Process>>#terminate, lying to us: "Since the receiver is not the active process, drop its priority to rock-bottom so that it doesn't accidentally preempt the process that is trying to terminate it." priority := 10. -- Best regards, Igor Stasenko AKA sig.

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A headless toolset?
by Eliot Miranda 02 May '09

02 May '09

Hi All. anyone have a headless analog to StandardToolSet that sends errors to standard out? I'm starting work on a new image format for Cog and am using John Maloney's MicroSqueak to generat ethe image. But I want more functionality than John's Hello World example. I want it to include the compiler and support scripting and filein so that I can bootstrap a full image from it. But I need a standard i/o based toolset to do this and it would be great if someone's already written it. TIA Eliot

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Some gotchas with #terminate and #critical:
by Igor Stasenko 02 May '09

02 May '09

Currently i replacing all calls which affect the scheduling to redirecting them to Processor, i.e. instead: self primitiveDoSomething do: Processor doSomethingWith: self. This is to ensure, that no code, in rest of classes , except ProcessorScheduler deals with scheduling directly. If i change the Semaphore>>wait method in that way, then it breaks the trick which sitting in #terminate method : "Figure out if we are terminating the process while waiting in Semaphore>>critical: In this case, pop the suspendedContext so that we leave the ensure: block inside Semaphore>>critical: without signaling the semaphore." (inSema == true and:[ suspendedContext method == (Semaphore compiledMethodAt: #critical:)]) ifTrue:[ suspendedContext := suspendedContext home. ]. What you think is following alternative implementation: critical: mutuallyExcludedBlock | blockValue caught | caught := false. [ caught := true. [self wait.] ifCurtailed: [ caught:=false ]. blockValue := mutuallyExcludedBlock value ] ensure: [caught ifTrue: [self signal]]. ^blockValue avoids the need in having tricks in #terminate? -- Best regards, Igor Stasenko AKA sig.

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[squeak-dev] Smalltalk #addtoStartUpList: , #addtoStartUpList: after:
by Igor Stasenko 01 May '09

01 May '09

I just discovered , that there is no way to add item to startup list to be the first or _before_ specified class. For instance, i can't insert AdvancedProcessorScheduler to be the first class who will receive #startUp: message. :( -- Best regards, Igor Stasenko AKA sig.

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[ANN] A new scheduler + VM changes alpha-release
by Igor Stasenko 01 May '09

01 May '09

Hello guys, i hope you are interested in having a rock-solid & safe concurrency in smalltalk, despite it green-threaded. A new implementation of scheduler will allow us to improve stuff and be no longer dependant from VM side scheduling policy. You can find the changes on mantis: http://bugs.squeak.org/view.php?id=7345 Please, give me a feedback, if you can successfully build VM with new changes on all platforms. I used a pretty old VMMaker package version for my VM: VMMaker-dtl.91 Will try to see if it can be built with latest one , available on SqS. Andreas (& others) - do you have any tests/benchmarks, how to measure a new scheduler overhead comparing to old one? Personally, i didn't noticed much speed degradation :) And last thing, i need an advice how to implement a #callbackEnter: properly. Its currently leaved unchanged, using old VM scheduling policy. So, its unsafe to use plugins with callbacks if you running under new scheduler. A callbackEnter remembers the active process, suspends it and then activates it back when callback is done. The problem is, that squeak 3.10 doesn't have any image-side code which i could change to play with callbacks :( A fix for callbacks should be pretty easy: - at entry, deactivate active process (which should be NOT the interrupt process) & switch to interrupt process, so it could schedule next available process. - when leaving switch from interrupt process to previously remembered active process. So, a certain preconditions should be met: - a code which calls a primitives which using callbacks should never run in interruptProcess - a code , which returns from a callback should run in interruptProcess -- Best regards, Igor Stasenko AKA sig.

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[RFI] A way to browse code saved with a *.pr project.
by Jerome Peace 01 May '09

01 May '09

Hi all, Problem: You develop an application in a project under one set of circumstances. Save the project out to disk. Them want to load it back in another entirely different set of circumstances. Some Browser or morph or something saved with the project doesn't want to load back in.* The story I would like to see implemented is: In addition to the option of loading the project 1) can I opt instead to load just the code associated with the project into a code browser. And/Or 2) save the code associated with the project as a fileout to the disk w/o loading the project at all. (Then filelist would allow the many things it knows to do with filed out code.) This story is strictly for .pr files. I know to generally save out a projects change set first before saving a project. I am looking for a way to ease things, particularly when I forget the extra steps. Yours in curiosity and service, --Jerome Peace *[ For me typically, I might be going from a fresh squeak 3.10.2 + development project over to etoys. Typically one gets tripped up by the etoys morphExtentionPlus. Or equally difficult from one of damian's squeak-dev images back to a fresh 3.10.2. In which case its the presence of an omnibrowser that creates loading problems.

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