Hi,
I have found a race condition: please can anyone help me isolate it?
I'm using 4.7.0.
Currently I have a requirement for environments in my widget rendering
code so I can't move to 4.8.0.
I have produced the repro case below. I originally saw the behaviour in
my app which uses spiffy, srfi-18 threads, environments and a host of
other eggs. This often causes spiffy requests to throw exceptions,
especially when there are lots of concurrent page-loads in progress.
-----
(use environments miscmacros srfi-18)
(define widget-eval-env (make-parameter (environment-copy
(scheme-report-environment 5) #t)))
(define (render-widgets sxml env default-bindings bindings contents)
(let ((add-attr (lambda (attr) (environment-set! env (first attr)
(second attr)))))
(if (list? default-bindings) (for-each add-attr default-bindings))
(if (list? bindings) (for-each add-attr bindings))
(environment-set! env 'contents contents)
(eval `(let ((++ string-append)) ,sxml) env))) ; Render the widget
(define (render sxml default-bindings bindings contents)
(let* ((env (environment-copy (widget-eval-env) #t))
(sxml (render-widgets sxml env default-bindings bindings contents)))
sxml))
(dotimes (t 10)
(thread-start!
(make-thread
(lambda ()
(printf "Hello ~A\n" t)
(dotimes (c 1000)
(render '`(test ,a ,b ,c)
'((c "Cee"))
`((a "Aay") (b "Bee") (c ,c))
'()))
(printf "Goodbye ~A\n" t)))))
-----
Running this in csi thusly:
-----
$ csi
...
#;1> (load "exn-repro.scm")
-----
Often results in an error such as the following:
-----
Warning (#<thread: thread88>): unbound variable: c
Call history:
<eval> (##sys#list (##core#quote test) a b c) <--
-----
Subsequent calls to '(load "exn-repro.scm")' in the same csi session do
not seem to produce the exception.
I have seen the unbound variable being many different things, including
"render" which is defined as a procedure in the top level.
I have been unable to reproduce this behaviour with a srfi-18 only case:
-----
(use miscmacros srfi-18)
(define (render sxml default-bindings bindings contents)
(cons (cons (cons bindings contents) default-bindings) sxml))
(dotimes (t 10)
(thread-start!
(make-thread
(lambda ()
(printf "Hello ~A\n" t)
(dotimes (c 100000)
(render '`(test ,a ,b ,c)
'((c "Cee"))
`((a "Aay") (b "Bee") (c ,c))
'()))
(printf "Goodbye ~A\n" t)))))
-----
I wonder if it's something to do with environments?
Does anyone have any tips for isolating this further?
Regards,
@ndy
--
[email protected]
http://www.ashurst.eu.org/
0x7EBA75FF
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