[Chicken-users] multi-threading bug in udp egg?

[David Janssens]

Hello,

 

I think I found a bug in the udp module.

Consider the following short program:

(require 'srfi-18 'udp)

(define (read-packets)
  (let loop ()
    (let ((s (udp-open-socket)))
      (udp-bind! s #f 6666)
      (receive (n data) (udp-recv s 2048)
        (print "packet received"))
      (loop))))

(thread-start! (make-thread read-packets 'read-packets))

(let loop ()
  (thread-sleep! 5)
  (print "beep")
  (loop))

The result of running this program with debugging output from scheduler.scm is:

DBG: #<thread: primordial> blocks for 5328
DBG: scheduling, current: #<thread: primordial>, ready: (#<thread: read-packets>)
DBG: timeout (328) list: ((5328 . #<thread: primordial>))
DBG:   #<thread: primordial> -> 5328
DBG: switching to #<thread: read-packets>

Obviously, there is a bug, since I would expect the message "beep" to be printed every 5 secs, independently of the read-packets thread. In this case, the udp-recv call seems to block everything.

I am running chicken 2.2 on cygwin (couldn't test on linux, sorry)

David Janssens