[graphic-forms-devel] SLIME and SBCL issues

[Jack Unrue]

I've been investigating a problem where starting a Graphic-Forms app from
within SLIME using the SBCL backend results in seemingly nothing but a hang.

What appears to be happening is that the message loop in GF is not even
getting past the first call to the Windows get-message function. I fired up
Winspector Spy, which is a utility for inspecting the window hierarchy, and
saw that application windows are getting created. But since no messages
are getting processed (except for maybe the very initial WM_NCCREATE
or WM_NCCSIZE), the windows don't appear and obviously are non-functional.

This problem has something to do with the combination of SLIME and SBCL,
since CLISP and SLIME work together ok as fas as GF is concerned. Also,
running SBCL from a command prompt works, albeit that's not nearly as
nice an environment.

So there are a couple workarounds right now (both assuming that you want
to use SLIME, rather than the LispWorks IDE). The first is to switch to CLISP
at least for the time being, as this is a configuration that works fine. The
second is to run SBCL from a command prompt.

It's important to keep in mind that SBCL/Win32 is currently still a
single-threaded
Lisp like CLISP is, so in both cases, the SLIME REPL would be queueing requests
until the message loop exits. When we see multi-threading support appear in
those Lisps, then hopefully we can get back our REPL while our GF apps are
running.

I've sent a query to the slime-devel list in the hopes of getting some pointers
to possible solutions, and I will continue to investigate this problem myself as
time allows.

-- 
Jack Unrue