[gambit-list] Symbol warning output made by (load) when making multiple (load):s in another thread than the primordial block the thread

Mikael More mikael.more at gmail.com
Tue Sep 23 05:29:19 EDT 2008


Hi!
We have been having a strange annoyance - probably very simple to solve -
for quite some while, and I wanted to address it here so that we and anyone
running into it might get around it.

What we do is to run a procedure that runs (load) multiple times in a
sequence, where the (load):s are such that they output multiple warnings
about unresolved symbols during the process. I'm well aware that unresolved
symbols are not acceptable in final code, but, during development, there may
be good reasons to prioritize other things than fixing symbol usage in code
that's not used in the present moment anyhow. As you know, the general
pattern for unresolved symbol warnings output by (load) is

*** WARNING -- Variable "some-module-name#some-function-name" used in module
"some-object-file.o1" is undefined


The problem is that when we execute the procedure from another thread than
the primordial, quite each of its warning output operations block (i.e. is
blocked / freezes / waits), and gets output to the console  first after that
one makes an evaluation in the REPL. Making a thread-sleep! or evaluating
zero is sufficient. After the evaluation, the procedure resumes until it
outputs another line, and then another evaluation needs to be made to make
it resume again, etc.

How do we make (load) never block, undepending of in what thread it is
executed?

Example code below.

Thanks
Mikael

 -

Set up test environment

echo "(define (test) (unknown-symbol-a) (unknown-symbol-b)
(unknown-symbol-c))" > a.scm
echo "(define (test) (unknown-symbol-d) (unknown-symbol-e)
(unknown-symbol-f))" > b.scm
echo "(define (test) (unknown-symbol-g) (unknown-symbol-h)
(unknown-symbol-i))" > c.scm

gsc
(compile-file "a.scm") (compile-file "b.scm") (compile-file "c.scm")
,q


Expected behaviour, load:s don't block:

gsc
(load "a") (load "b") (load "c")
,q



Output is:

> (load "a") (load "b") (load "c")
"/home/mikael/a"
> *** WARNING -- Variable "unknown-symbol-d" used in module "b.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-e" used in module "b.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-f" used in module "b.o1" is
undefined
"/home/mikael/b.o1"
> *** WARNING -- Variable "unknown-symbol-g" used in module "c.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-h" used in module "c.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-i" used in module "c.o1" is
undefined
"/home/mikael/c.o1"


Unexpected behaviour, load:s block:

gsc
(thread-start! (make-thread (lambda () (load "a") (load "b") (load "c"))))


Output is:

#<thread #2>
>

(thread-sleep! 5)
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-d" used in module "b.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-e" used in module "b.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-f" used in module "b.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-g" used in module "c.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-h" used in module "c.o1" is
undefined
*** WARNING -- Variable "unknown-symbol-i" used in module "c.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
>


Alternatively:


#<thread #2>
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-a" used in module "a.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-b" used in module "a.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-c" used in module "a.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-d" used in module "b.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-e" used in module "b.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-f" used in module "b.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-g" used in module "c.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-h" used in module "c.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
------------- REPL is now in #<thread #2> -------------
*** WARNING -- Variable "unknown-symbol-i" used in module "c.o1" is
undefined
------------- REPL is now in #<thread #1 primordial> -------------
> 0
0
> 0
0
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