Squeak-dev October 1999

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396 discussions

[BUG] MVC System Browser Problems
by Dean_Swan＠Mitel.COM 28 Oct '99

28 Oct '99

Under MVC, it seems that the System Browser is quite broken with respect to adding new classes, methods, and method categories, all of which seem to work fine in a Morphic project. I'll look at this as time allows, but I thought I'd post it also, since someone may have already fixed this, and if not, many on the list will be able to find the problem(s) and effect repairs more quickly than I can. -Dean Swan dean_swan(a)mitel.com

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Re: Need Squeak for Mac 68030/68881, or Linux 2.036 M68K?
by John M McIntosh 28 Oct '99

28 Oct '99

> > > John M McIntosh wrote: >> >> In case anyone really wants a version of Squeak 2.5 for a 68030 mac with >> 68881 support, or perhaps a version of Squeak 2.6 for a m68K linux 2.0.36 >> machine (IE a Quadra 950 running Linux). >> >> Let me know since I've compiled up two VMs. >> > Are you gonna do Amiga too :)))) ?? > > No, I've only a Vic20 about, but I'm not sure Squeak will fit into RAM yet... -- =========================================================================== John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com =========================================================================== Custom Macintosh programming & various Smalltalk dialects PGP Key: DSS/Diff/46FC3BE6 Fingerprint=B22F 7D67 92B7 5D52 72D7 E94A EE69 2D21 46FC 3BE6 ===========================================================================

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Re: TrueType font hackery - who wanted it?
by Robin Gibson 28 Oct '99

28 Oct '99

If you don't mind, I'd like a crack at integrating it with the stuff I've already done... .... so add me to the list of recipients. - Robin Tim Rowledge <rowledge(a)interval.com> wrote: > Somebody asked for the changeset I have that makes an ugly hack at doing some > stuff with TT fonts. Can't remember who it was now I'm at work and can find > the .cs, of course! > > tim > > -- > Fractured Idiom:- ICH LIEBE RICH - I'm really crazy about having dough > Tim Rowledge: rowledge(a)interval.com (w) +1 (650) 842-6110 (w) > tim(a)sumeru.stanford.edu (h) <http://sumeru.stanford.edu/tim>

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Re: Need Squeak for Mac 68030/68881, or Linux 2.036 M68K?
by John M McIntosh 28 Oct '99

28 Oct '99

> On Wed, 27 Oct 1999, Mark Guzdial wrote: > >> How does Morphic performance feel? That's about half the benchmark numbers >> of my Powermac 6100/66, and it does feel reasonable in Morphic. I have a >> Quadra 800 sitting on the floor here that I wouldn't mind Linux-izing if >> the result was a reasonable-feeling Squeak machine. > > I'm using a Quadra 800 as my regular desktop machine - and Morphic > performance is terrible - I assume because it doesn't use the floating > point chip. > > ************************************************************************** > Network Technology Corporation PO Box 600618 > Miles R. Fidelman, President Newtonville, MA 02460-0006 > mfidelman(a)ntcorp.com 617-558-3698 > http://www.ntcorp.com fax: 617-630-8946 > ************************************************************************** > > Ok I ran some quick tests For a Macintosh IIvx, a 32Mhz 68030, with 68882. 32K L2 cache. "Yet another simplified code example, no I didn't want to wait a million iterations" Time millisecondsToRun: [100000 timesRepeat: [10.0+5.0/18.88*9.77-5.77]] The 2.5 VM without 68882 support as shipped took 82319 & 80194 milliseconds My recompiled VM with 68882 support took 63128 & 62662 milliseconds Perhaps I'll reboot the 950 with a Mac OS and see how long it takes to run the code example. But for now note the 950 took only 17410 & 17330 milliseconds (The 950 being a 66Mhz 68040 with 8K L1 cache) But of course the question really is how much floating point math do you do? (Another question is performance under macos and compiler, versus under Linux and GCC) -- =========================================================================== John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com =========================================================================== Custom Macintosh programming & various Smalltalk dialects PGP Key: DSS/Diff/46FC3BE6 Fingerprint=B22F 7D67 92B7 5D52 72D7 E94A EE69 2D21 46FC 3BE6 ===========================================================================

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Re: Reference counting
by John M McIntosh 28 Oct '99

28 Oct '99

> Hi, John: > > So what's your conclusion about weak references from these > experiences? What do you think of Squeak's implementation of them, > which avoids some of the problems you mention below? > Mmm you asked... But I'll answer indirectly, mostly because I need more time to comment, perhaps yet another late late night snack at OOPLSA? However I took a few hours off of working on my website and looked at WeakKeyDictionary. I tried the following code. | weakD aK bK aV bV | weakD := WeakKeyDictionary new. aK := String fromString: 'aK'. bK := String fromString: 'bK'. aV := String fromString: 'aV'. bV := String fromString: 'bV'. weakD at: aK put: aV. weakD at: bK put: bV. aK := nil. bK := nil. Smalltalk garbageCollect. Transcript show: weakD printString. => WeakKeyDictionary (nil->'bV' nil->'aV' ) Mmmm not quite what I expected. I believe there isn't a call to WeakArray(class)>>addWeakDependent: so WeakKeyDictionary>>finalizeValues never is invoked. Is this a bug? So I did | weakD aK bK aV bV | weakD := WeakKeyDictionary new. WeakArray addWeakDependent: weakD. aK := String fromString: 'aK'. bK := String fromString: 'bK'. aV := String fromString: 'aV'. bV := String fromString: 'bV'. weakD at: aK put: aV. weakD at: bK put: bV. aK := nil. bK := nil. Smalltalk garbageCollect. Transcript show: weakD printString. =>WeakKeyDictionary () -------------------------------- Better. Now lets setup the issue: | weakD aK bK aV bV | weakD := WeakKeyDictionary new. WeakArray addWeakDependent: weakD. aK := String fromString: 'aK'. bK := String fromString: 'bK'. aV := String fromString: 'aV'. bV := String fromString: 'bV'. weakD at: aK put: aV. weakD at: bK put: aK. aK := nil. bK := nil. "Note the two garbage collections" Smalltalk garbageCollect. Transcript show: weakD printString. Smalltalk garbageCollect. Transcript show: weakD printString. "Results" =>WeakKeyDictionary ('aK'->'aV' ) =>WeakKeyDictionary () So two GC events are required to cleanup the dictionary, can you guess why? Can anyone state the solution? Could this cause interesting effects? -- =========================================================================== John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com =========================================================================== Custom Macintosh programming & various Smalltalk dialects PGP Key: DSS/Diff/46FC3BE6 Fingerprint=B22F 7D67 92B7 5D52 72D7 E94A EE69 2D21 46FC 3BE6 ===========================================================================

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Re: Reference counting
by John M McIntosh 28 Oct '99

28 Oct '99

> To address the original issue, which is how to manage > an in-memory cache of objects such as pre-rendered glyphs > from a large Asian character set: I would update a timestamp > each time a particular glyph was requested. When the cache > got too large, I'd remove the least recently used glphs > from the cache. If the glpyh has no other references, it > will be garbage collected. (I might invoke a full GC > after cleaning up the cache to force the space to be > reclaimed immediately.) > This is good, but if you look on the web for LRU and VM you'll find lots of material discussion how to determine which VM page should go out and hope that it's not needed in the near future, avoiding page thrashing. This of course is very similar to the problem you are solving. John Maloney mentioned LRU, there is FIFO (first in, first out) Keep an linked list of glyphs, when you access one move it to the head of the list. On memory shortage take glyphs off the tail of the list. This could be faster I'm not sure about the suggestion about creating all those timestamp objects, also you'd need to inspect all the glyphs to find the oldest. However for LRU there are algorithms to attempt LRU but minimize work effort. -- =========================================================================== John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com =========================================================================== Custom Macintosh programming & various Smalltalk dialects PGP Key: DSS/Diff/46FC3BE6 Fingerprint=B22F 7D67 92B7 5D52 72D7 E94A EE69 2D21 46FC 3BE6 ===========================================================================

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RE: More on 3D speed
by Raab, Andreas 28 Oct '99

28 Oct '99

> > > A Java Quake level viewer worked OK on a P2/300 with the IE4 VM. > > Do you know what kind of 3D API this viewer used?! (probably D3D > retained > > mode) > > Software rendering. This was the impressive part. > Very impressive, indeed! Is that stuff publicly available somewhere?! Andreas -- +===== Andreas Raab ========= (andreasr(a)wdi.disney.com) ==+ | Walt Disney Imagineering Phone: +1 818 544 5016 I I Glendale, CA Fax: +1 818 544 4544 I +======< http://isgwww.cs.uni-magdeburg.de/~raab >========+

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Re: Reference counting
by John M McIntosh 28 Oct '99

28 Oct '99

> "John M McIntosh" <johnmci(a)ibm.net> wrote... > [and I think John actually knows most of what's here. I just felt there was more to be said] >>As pointed out one of the strange things that one can do in some flavors of >>Smalltalk is take back an about to be GCed object. As part of finalization >>you can make a strong reference and effectively forbid the GCing of the >>object. Mind you it makes my head hurt why you would want to do this! > > Well, in a perfect world, you should never have to. But there are reasons. > Usually they have to do with tracking some other system without the > benefit of actual references. The most common example is to close or > delete a file when ST no longer refers to it. If the file operations were > embedded in a transaction, then control could not emerge to the point of > releasing the file without proper wrap-up. Or if the file mechanism were > all in ST (*), the GC could sweep it away and no one would be the wiser. > That's how it's supposed to be. But the truth is that there usually IS > another reference to the bits on the disk, but ST can't see it. So > finalization in such cases provides a mechanism for ST to retrieve the > external reference, make it visible, and complete the transaction in an >appropriate manner. > Agreed, the other case were I've seen this type of pattern used is dealing with external OS database session. However both these cases deal with having Smalltalk sync or do housekeeping between it's viewpoint and the hosting OS. I'm more interested in hearing about examples where one would take back about to be GCed object as part of solving a business problem. {Regarding your cache flushing at close/GC time. Apple did this quite a number of years ago and it had one problem. If your cache was very large, and if you had lots of dirty blocks, then on the close flushing all those blocks took a long long time since each block was a separate I/O} >>Regarding Latency, an example. Given this simplified code >> >>thing isAnOrange ifTrue: [Transcript show: thing color] >> >>Many times I've seen a walkback, nil does not understand color, but what >>happened, how could thing which just responded to the isAnOrange message >>become nil? Well a GC occur and thing just well disappeared. > > Let me know if this ever happens in Squeak. I don't believe this > particular example is in any gray area -- it's flat wrong. The variable > 'thing' should hold onto its referent throughout this expression. I can't >imagine using a system with this problem. > > I have seen such a thing happen in Smalltalk, but it was due to a > reentrancy bug where there was shared access to the variable 'thing', > another process got tirggered between the two sends, set 'thing' to nil, and >then gave control back. But that's not what you were talking about. > > I can also imagine a perverse situation where isAnOrange does a become >operation, but that's not what you were talking about either. > > - Dan > Dan you are correct my example is poor and has been too simplified, that's what I get when I talk about weak references late at night, the dog wanted out, I was in a hurry etc. But I did twitch when I hit the enter key last night, and today I'm paying for it since I had to go back and dig out my notes to better explain what I was REALLY talking about. >>thing isAnOrange ifTrue: [Transcript show: thing color] As Dan points out the example is flawed without additional knowledge. 'thing' of course usually is an instance variable or a temp and firmly attached to the execution context so it's not going to GC heaven. But in my notes I've two examples The first example deals with Corba based Smalltalks, after building a few you forget how specialized they are. The Corba ORB in your image keeps weak references to your objects so you don't have to tell the ORB when to GC them, and of course to enable objects to get GCed when they need to be GCed. If the Orb kept a strong reference then someday you'd have problems because you'd forget to make that little call to sync your view of garbage with it's view. Example 1 | thing | thing := Foo new asCorbaObjectReference thing isAnOrange ifTrue: [Transcript show: thing color] This may or may not fail when we execute the ifTrue statement since 'thing' of course is not an instance of Foo, it's a Corba Object Reference which weakly refers to the instance of Foo you've created. The 'thing' or I should say Corba proxy uses information contained within it to hunt down the actual object and execute the method against it and return the results, it all happens transparent via doesNotUnderstand, just step over it and it behaves like any other message send. Problem with this code fragment is that we no longer have a strong reference to the instance of Foo we just created. So based on when finalization occurs different results can happen. Visual clues, when clouded by other code, certainly don't show you that it's a Corba call so unless you knew that 'thing' was an Corba Object Reference versus an instance of Foo you would be quite confused when 'thing color' failed. Example 2 This problem occurred when a developer got a hold of a weak reference to a database session and as far as he was concerned it was strong. It work just fine until the session was closed and the strong reference disappeared. Again a specialized case where you deal with weak references as if they were strong. At least in Visualworks when you get 0 does not understand the message color then perhaps you were dancing too much on the edge of weak references, or was that razor blades. I hope I didn't confuse anyone too much and would be glad to answer any further questions about finalization etc.. -- =========================================================================== John M. McIntosh <johnmci(a)smalltalkconsulting.com> 1-800-477-2659 Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com =========================================================================== Custom Macintosh programming & various Smalltalk dialects PGP Key: DSS/Diff/46FC3BE6 Fingerprint=B22F 7D67 92B7 5D52 72D7 E94A EE69 2D21 46FC 3BE6 ===========================================================================

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Jun for Squeak?
by Richard L. Peskin 28 Oct '99

28 Oct '99

Has anyone recently given consideration of a port of Jun (OpenGL classes for VW) to Squeak? --dick peskin ================================= R. L. Peskin, Rutgers Univ. ;<peskin(a)caip.rutgers.edu>;<http://www.caip.rutgers.edu/~peskin> RLP Consulting <rlpcon(a)sover.net>; <http://www.sover.net/~rlpcon>

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Re: More on 3D speed
by Eric Ulevik 28 Oct '99

28 Oct '99

From: Raab, Andreas <Andreas.Raab(a)disney.com> > > A Java Quake level viewer worked OK on a P2/300 with the IE4 VM. > Do you know what kind of 3D API this viewer used?! (probably D3D retained > mode) Software rendering. This was the impressive part. > > If Squeak can use an external OpenGL library, then things are easy. > Be precise - it might be easy but it is not necessarily fast. It is amazing > how slow some of the GL stuff is because people do not understand the > tradeoffs (e.g., if you are using glVertex()/glTexCoord() to submit your > vertices and attributes separately don't expect your stuff to be blazingly > fast). True - I should have said "requires less coding". Making things fast always requires measurement. Intuition often fails. In my current C++ project, we find that .c_str() is taking 70% of CPU in a certain task. And there I was thinking that reading hundreds of data items off a hard disk was going to be the bottleneck. Wrong again! Regards, Eric Ulevik

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