Some questions and comments
Doug Way
dway at riskmetrics.com
Thu Mar 14 00:59:48 UTC 2002
Bill Schwab wrote:
>
> The following are some questions and comments based on a little
> "real" work in Squeak. This has occured on a confusing mix of
> versions and platforms. When in doubt, assume 3.2 gamma,
> Win98 on a P2-400, though I've done some of it on NT4 and some
> on a P-200 running Win95. The goal was to get Squeak to read
> incoming MIDI data and to display it in a variety of morphs. It
> works (for a while anyway, see below) but, isn't anything to brag
> about yet.
>
> First, an aside on 3D graphics: the only time that I've crashed
> Squeak was by enabling (well, trying to anyway<g>) hardware
> acceleration on the Explore 3D morph. I'm actually glad it
> happened, because it showed me that Squeak has a crash dump;
> does the dump feature also exist on Linux?
I believe all platforms will output a crash dump, but I'm not positive.
> I have managed to get Squeak to lock up though. Some of it is
> probably my fault, but, in 3.0 again playing with the Explore 3D
> morph, I find that by "running into the cube", I can get Squeak to
> freeze to the point that I have to kill it from the task list.
>
> In 3.2 gamma at least, I've had some less extreme freezes, some
> of which happened while experimenting with Morphic, and I think
> they were definitely my fault. It was generally possible to control-
> c/break into a debugger, at least on a P2-400.
>
> During some MIDI experiments on a P-200, I've had some freezes
> that control-break won't interrupt. Squeak's message loop appears
> to be running though, because it will shut down via the [x] on the
> title bar. It's possible that the work load is too much to ask of the
> machine, though the IDE runs fairly well on it. The choice of
> machine was mostly due to having a hand-me-down box that
> wasn't doing anything and happens to be MIDI-aware. A faster
> machine will become available in the near future.
>
> Any suggestions for figuring out why Squeak locks up in any given
> case?
There is a FAQ item on the swiki about "What to do if Squeak crashes/freezes" that you may want to look at: http://minnow.cc.gatech.edu/squeak/2168
> Again, a lot of my trouble could be inadequate hardware for
> the MIDI application. However, I also get a non-breakable lockup
> when loading Bob's UI into 3.2 gamma. Any suggestions for how
> one would debug that?
The FAQ page covers this a little bit... I think that a freeze is usually either caused by the VM hanging (which is unusual), or by a higher-level Squeak process running in an infinite loop. The Process Browser/CPUWatcher might be able to help with this second case.
(It's useful to know that loading BobsUI in 3.2gamma is a repeatable way to get a freeze, if that's true. I've been (casually) maintaining BobsUI lately anyway, so I should probably look at it. :-) )
> It seems fairly common for window resizing to leave Morphic in a
> confused state; restore display fixes it, but, I find myself falling
> back on that too often. Disabling "Defer display udpate" appears to
> fix it, but, (I think) at some performance penalty???
>
> Squeak's appearance has improved a lot recently. The feel is still
> a little off, and my past comment that it would be hard to sell a
> Squeak app to clerical users stands; please don't underestimate
> the value of the kind of data they enter into machines, nor the
> volume of their complaints when asked to reach for a mouse.
With some work, it would be possible to create an end-user application which didn't require use of the mouse. It would have to be pretty restrictive, though.
- Doug Way
dway at riskmetrics.com
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