gtk-timeout-add function stalling

[Paul Emsley]

Hi,

I am trying to update a progress bar that is downloading a file using 
libcurl in a thread.  I am doing that by adding a timeout function that 
every fraction of a second or so queries the status of the download 
(curl-progress-info).  However, after a number of rounds (somewhere 
between 100 or 250) the timeout function seems to hang - even partway 
through writing a debugging text. (The thread downloading the file 
continues.)  Why does the timeout function stalling?

[with guile 1.8.7 embedded]

Thanks,

Paul.


------

Here's a fragment:


    ... setup the dialog....

    (gtk-signal-connect ok-button "clicked"
         (lambda ()
              (call-with-new-thread
                (lambda ()
                  (if (not (run-download-binary-curl revision 
version-string))
                    (set! pending-install-in-place 'fail)))
                updates-error-handler)))


    ... more setting up ...

   (gtk-timeout-add
      500 (lambda ()
        (cond
         ((eq? pending-install-in-place 'fail)
          (gtk-widget-destroy window)
          (info-dialog "Failure to download and install binary")
          #f)
         (else
          (update-progress-bar progress-bar)
          #t))))

 ;;
 (define update-progress-bar
   (let ((count 0)
         (active-count 0))
   (lambda (progress-bar)
     (set! count (+ count 1))
     (if (string? file-name-for-progress-bar)
       (let ((curl-info (curl-progress-info file-name-for-progress-bar)))
         (set! active-count (+ active-count 1))
         (if curl-info
           (let ((v1 (assoc 'content-length-download curl-info))
                 (v2 (assoc 'size-download           curl-info)))
             (if (list v1)
                (if (list v2)
                   (let ((f (/ (cdr v2) (cdr v1))))
                       (format #t "count ~s, active-count ~s, f: ~s~%" 
count active-count f)
                       (gtk-progress-bar-update progress-bar f)))))))))))