[plt-scheme] Re: hint for debugging file navigator freezing bug in DrScheme 4.1.1, english, on Windows XP Professional, Service Pack 2

From: Eli Barzilay (eli at barzilay.org)
Date: Mon Oct 13 17:36:22 EDT 2008

On Oct 10, Benjamin L.Russell wrote:
> On Thu, 9 Oct 2008 23:42:42 -0400, Eli Barzilay
> <eli at barzilay.org> wrote:
> >On Oct 10, Benjamin L.Russell wrote:
> >> 
> >> Previously, discussion of this bug had led to the hypothesis that
> >> perhaps it had been caused by Windows itself as a result of
> >> navigating through local folders on a networked computer.
> >
> >That still sounds like the most likely option -- the save dialog on
> >Windows is the standard Windows dialog, and while the dialog is up,
> >there is no Scheme code that does anything with it.
> Aha!  That's why!  I just visually compared the file navigators for
> DrScheme and newLISP, and discovered that while the navigator for
> DrScheme is the standard Windows dialog, the one for newLISP
> apparently seems a part of newLISP itself, and behaves as a separate
> window for a Windows application program.

That's why it's better to use the native Windows dialog.

> Here are links to hosted snapshots of the three files:
> [...]

It looks like they're also using the native Windows dialog.

> Probably the newLISP developers ran into exactly the same problem
> with the Windows file navigator, and decided to re-create a
> non-buggy version of the file navigator to avoid this specific
> problem.  Their navigator runs as a separate Windows application
> program, and not as the standard Windows dialog box.  Somehow, this
> resolves the problem, and their file navigator does not hang.

I'm not sure that this is what motivated any kind of change.  The fact
is that the most popular platform PLT is used on is Windows
(unsurprisingly), but I have not heard of such issues until your
message.  (I'm also using Windows on occasions, and never had such a

> >Now, it might be that things are setup in a way that causes such
> >delays.  But to be able to start debugging it, we need some
> >practical way to recreate the problem.
> To recreate the problem, just start DrScheme on Windows XP
> Professional, Service Pack 2, and start navigating through a dozen
> or so directories.  At some point, your standard Windows navigator
> will suddenly freeze for a few seconds.

I've done that.  Just in case, I re-did it now, and I counted at least
a 100 directory changes with no visible freeze.  (I did go to system
directories, directories with many scheme files and few scheme files,
directories with big files, the root, "my computer", etc.)  My system
is also XP with SP2.

On Oct 10, Benjamin L.Russell wrote:
> I just thought of an even easier solution: Since their application
> is open-source and is licensed under the GNU GPL (Version 3), just
> copy and modify their source code for their navigator, and apply it
> to DrScheme.  No need to reinvent the wheel!

We have a Scheme-version of the open/save dialogs -- they're being
used on the Unix platforms.  But still the advantages of a native
dialog are greater than being able to tweak the code.

          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!

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