Squeak-dev October 2004

squeak-dev@lists.squeakfoundation.org

156 participants
313 discussions

[FIX][KCP] KCP-0112-FixCanUnderstand
by n.schaerli＠gmx.net 06 Dec '04

06 Dec '04

from preamble: "Change Set: KCP-0112-FixCanUnderstand Date: 12 December 2003 Author: Nathanael Schaerli Fixes canUnderstand so that it deals with abstract methods (i.e., subclassResponsibility and shouldNotImplement) in the right way."!

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[BUG] printShowingDecimalPlaces:
by Pavel Krivanek 26 Nov '04

26 Nov '04

111.2 printShowingDecimalPlaces: 2 -> '111.20' 111111111111111 printShowingDecimalPlaces: 2 -> '1.11' 123e20 printShowingDecimalPlaces: 2 -> '1.23' 10 printShowingDecimalPlaces: 20 -> Error: subscript is out of bounds: 21 Pavel

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Mantis: New Categories
by Marcus Denker 15 Nov '04

15 Nov '04

Hi, There is now a new top-level categories on Mantis for reports that are about bugs that are in packages not part of Squeak full (e.g. connectors, Jabber, Whisker). The categorie is "Squeak ext packages". If someone needs a new sub-category for a project, please send a mail and I add it. For the "Squeak" Main category, we can add sub-categories on demand. (e.g for all packages in full). If the "Squeak" category gets to full at some point, we might splitt it in "Squeak Image" and "Squeak official Packages" (e.g. Yaxo, Monticello, Scamper). Marcus

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Seaside tutorial
by Alexandre Bergel 05 Nov '04

05 Nov '04

Hi! I made a tutorial I plan to use for a seaside lecture. It can be downloaded from http://www.iam.unibe.ch/~scg/Teaching/Smalltalk/Seaside.pdf I would be glad for any kind of comments/feedback/English bug fixes :-) Cheers, Alexandre -- _,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;: Alexandre Bergel http://www.iam.unibe.ch/~bergel ^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;._,.;:~^~:;. _______________________________________________ Seaside mailing list Seaside(a)lists.squeakfoundation.org http://lists.squeakfoundation.org/listinfo/seaside

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I2C Serial Port in Squeak
by Jon Hylands 05 Nov '04

05 Nov '04

Hi everyone, I have a question for the VM guys -- I'm planning on using an I2C bus on my next autonomous robot, and the Squeak machine I'm going to use (www.gumstix.com) has a hardware I2C interface, with a driver for it in Linux. As far as I can tell, the I2C port looks just like another device in Linux, so I'm hoping I can just use the serial port with a different com port #. Any thoughts? Later, Jon -------------------------------------------------------------- Jon Hylands Jon(a)huv.com http://www.huv.com/jon Project: Micro Seeker (Micro Autonomous Underwater Vehicle) http://www.huv.com

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REMINDER: Harvesting Party Monday November 1st 16:00 GMT
by Ken Causey 05 Nov '04

05 Nov '04

Just a reminder that the next Harvesting Party will take place between 16:00 (4 PM) and 20:00 (8 PM) GMT Monday November 1st, 2004. As usual we will meet in #squeak on irc.freenode.net. More information about the #squeak IRC channel can be found at http://people.squeakfoundation.org/article/7.html Information about the Harvesting Party idea can be found at http://people.squeakfoundation.org/article/29.html If you have the time please attend and work toward the future of Squeak. The next seven parties are scheduled for 20:00 (08:00 PM) GMT Friday November 05, 2004 00:00 (12:00 AM) GMT Wednesday November 10, 2004 04:00 (04:00 AM) GMT Sunday November 14, 2004 08:00 (08:00 AM) GMT Thursday November 18, 2004 12:00 (12:00 PM) GMT Monday November 22, 2004 16:00 (04:00 PM) GMT Friday November 26, 2004 20:00 (08:00 PM) GMT Tuesday November 30, 2004

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Alan's ACM talk at OOPLSA 2004
by John M McIntosh 05 Nov '04

05 Nov '04

As usual I've taken some notes about Smalltalk at OOPLSA and have posted coverage of Alan's talk at http://wiki.cs.uiuc.edu/CampSmalltalk/OOPSLA+2004+Trip+report Please take a peek and because it's a wiki make any corrections or provide more material. -- ======================================================================== === John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ======================================================================== ===

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PDA and Squeak
by Squeak Smalltalk 03 Nov '04

03 Nov '04

Hi, I want to have a PDA that I can have in my pocket and that runs Squeak. Which one shall I buy in Europe? Is someone crazy like me and runs squeak on a pda ? Best Regards W.

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Garbage Collection in Squeak
by John M McIntosh 03 Nov '04

03 Nov '04

As some of you know I from time to time do serious GC tuning in VisualWorks. http://www.smalltalkconsulting.com/papers/GCPaper/GCTalk%202001.htm For years now (yes years) I've been thinking about doing serious tuning in Squeak, but yet things just weren't interesting enough. However with the release of Croquet, thoughts on TK4, and mumblings from folks I turned my eye upon what the Squeak GC was doing. First thanks to Ted Kaehler (among others) for writing this GC 10 odd years back which we've run with little change over the years until we added the ability to shrink/grow the memory space a few years back. First I'll need some help from macintosh users that have interesting images and can run a pending 3.8.4 mac VM with instrumentation and then send me some diagnostic log. People who are willing to help should email me directly, and I'll get you a VM and changeset, and we'll see if we can fill up my gmail account with log data. I'm very interested in getting Croquet data, having a test case you can run before/after would be best. So lets review how does the Squeak GC work: A simplistic view is that your image (25MB) is loaded into Old Space, and 4MB (set in Smalltalk) is allocated for Young Space. After allocating 4000 (if they fit) new object (limit set in smalltalk) we do an mark/sweep/compacting GC on young space using the VM roots plus roots identified from Old Space to Young Space references. Normally this means looking only at a few thousand objects, then occasionally we might do a full GC across all 300K object based on various conditions, but that's rare. I'll note the Old Space to Young Space remember table, remembers the Object containing the reference, not the reference so that if you have 100,000 element collection we interate over all 100,000 entries looking for the 1 or more old to young references, a cause for performance concern. If after completing the mark/sweep/compaction and over 2000 objects (set in Smalltalk) are survivors we "Tenure" them to old space by moving the old/young pointer boundary, then start allocating objects again, mind if the young space exceeds now 8MB free (set in smalltalk) we given memory back and reset things back to the 4MB boundary. Now object allocation can end early because we are allocating a big object, in that case we do an young GC, followed by a full GC (very expensive) followed by growing young space so the big object can fit. Also of course if we run out of root table remember space, we end the allocation process early and think about Tenuring things. Or it can end if we drop below a minimum amount of memory (200K set by smalltalk) which makes the image grow, which if it fails signals the low space semaphore (and brings up a low space dialog which no-one really see and have bitterly complained about) Yes I now know why that occurs too... The Problem: Last weekend I built a new VM which has instrumentation to describe exactly what the GC is doing, also to trigger a semaphore when an GC finishes, and to allow you to poke at more interesting things that control GC activity. What I found was an issue which we hadn't realized is there, well I'm sure people have seen it, but don't know why... What happens is that as we are tenuring objects we are decreasing the young space from 4MB to Zero. Now as indicated in the table below if conditions are right (a couple of cases in the macrobenchmarks) why as you see the number of objects we can allocate decreases to zero, and we actually don't tenure anymore once the survivors fall below 2000. The rate at which young space GC activity occurs goes from say 8 per second towards 1000 per second, mind on fast machines the young space ms accumulation count doesn't move much because the time taken to do this is under 1 millisecond, or 0, skewing those statistics and hiding the GC time. AllocationCount Survivors 4000 5400 3209 3459 2269 2790 1760 1574 1592 2299 1105 1662 427 2355 392 2374 123 1472 89 1478 79 2 78 2 76 2 76 2 Note how we allocate 76 objects, do a young space GC, then have two survivors, finally we reach the 200K minimum GC threshold and do a full GC followed by growing young space. However this process is very painful. Also it's why the low space dialog doesn't appear in a timely manner because we are attempting to approach the 200K limit and trying really hard by doing thousands of young space GCed to avoid going over that limit. If conditions are right, then we get close but not close enough... What will change in the future. a) A GC monitoring class (new) will look at mark/sweep/Root table counts and decide when to do a tenure operation if iterating over the root table objects takes too many iterations. A better solution would be to remember old objects and which slot has the young reference but that is harder to do. b) A VM change will consider that after a tenure if the young space is less than 4MB then growth will happen to make young space greater than 4MB plus a calculated slack. Then after we've tenured N MB we will do a full GC, versus doing a full GC on every grow operation, this will trigger a shrink if required. For example we'll tenure at 75% and be bias to grow to 16MB before doing full GC. c) To solve hitting the hard boundary when we can not allocate more space we need to rethink when the low semaphore is signaled and the rate of young space GC activity, signaling the semaphore earlier will allow a user to take action before things grind to a halt. I'm not quite sure how to do that yet. Some of this might be back-ported to earlier VM, I think so, yet I won't know until we gather more data and try a few things. -- ======================================================================== === John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com ======================================================================== ===

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Unit tests failing in clean image
by Rob Lally 02 Nov '04

02 Nov '04

Hi, I just downloaded, unpacked and ran Squeak 3.7 for windows. I popped open the SUnit test runner and ran the tests. A bunch of them failed and some required me to manually intervene. Is this normal, or have I done something wrong? If it is normal .... why? Is there anything I can do to fix it; other than just deleting all of the tests - which seems wrong. I'm a proponent of TDD and I can't live with a system where tests fail every time I run them. R.

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