[racket] distributed places - throwing dcgm-type contract violation on *channel-get

The following thunk example works for me.
Uncommenting the message-router line will pump back stdout and stderr 
from the remote node so you can see any errors that may be occurring at 
the remote-node.
You will have to kill the message router by hitting CTRL-C when you want 
to end the program.


EXAMPLE 1
-----------------------------------------
#lang racket
(require racket/place/distributed)
(define (hello-world)
   (place ch
     (printf/f "hello-world received: ~a\n" (place-channel-get ch))
     (place-channel-put ch "Hello World\n")
     (printf/f "hello-world sent: Hello World\n")))
(provide hello-world)

(module+ main
   (define-values (node pl) (spawn-node-supervise-place-at "localhost" 
#:listen-port 7000 "hello-world-place.rkt" 'hello-world #:thunk #t))
   (*channel-put pl "Hello bozo")
   (*channel-get pl)
   #;(message-router node)
   )


Example 2 show how I would normally write distributed places code 
without using the #:thunk keyword argument.

EXAMPLE 2
--------------------------------------------
#lang racket
(require racket/place/distributed)
(define (hello-world ch)
   (printf/f "hello-world received: ~a\n" (place-channel-get ch))
   (place-channel-put ch "Hello World\n")
   (printf/f "hello-world sent: Hello World\n"))
(provide hello-world)

(module+ main
   (define-values (node pl) (spawn-node-supervise-place-at "localhost" 
#:listen-port 7000 "hello-world-place.rkt" 'hello-world))
   (*channel-put pl "Hello bozo")
   (*channel-get pl)
   #;(message-router node)
   )


On 12/15/2012 02:16 AM, Matthew Eric Bassett wrote:
> Just to update, also tried this on v5.3.1 using 
> spawn-node-supervise-place-at with #:thunk set.  same result.
>
> On 12/14/2012 03:31 PM, Matthew Eric Bassett wrote:
>> Hey folks,
>>
>> I was playing around with distributed places and I ran into a some 
>> problems.  I'm using racket v5.3 and am following the docs from the 
>> racket reference 
>> (http://docs.racket-lang.org/reference/distributed-places.html)
>>
>> Let's say we have an example just like the one in the reference.
>>
>> hello-world-place.rkt
>> ----------------------
>> (define (hello-world)
>>     (place ch (printf "hello-world received: ~a\n" (place-channel-get 
>> ch))
>>     (place-channel-put ch "Hello World\n")
>>     (printf "hello-world sent: Hello World\n")))
>>
>> Then from the racket xrepl we do
>>
>> >> (define-values (node pl)
>>             (spawn-node-supervise-dynamic-place-at remote-node 
>> "hello-world-place.rkt" 'hello-world))
>> ; there's now a racket process running on my remote-node
>> >> (*channel-put pl "hi")
>> ; the remote node shuts down as we expect, giving the 
>> place-channel-get should have locked it until this point.
>> >> (*channel-get pl)
>> ; dcgm-type: contract violation
>> ;   expected: dcgm?
>> ;   given: #<eof>
>> ;   context...:
>> ; /usr/local/lib/racket/collects/racket/place/distributed.rkt:442:8: 
>> loop
>> ;    /usr/local/lib/racket/collects/xrepl/xrepl.rkt:1341:0
>> ;    /usr/local/lib/racket/collects/racket/private/misc.rkt:87:7
>>
>> I've tried [naively] using place-channel-put/get instead of 
>> *channel-put/get, same result.  Wrapping it in a message-router makes 
>> no difference.
>>
>> >> (message-router node (after-seconds 2 (*channel-put pl "hi!") 
>> (*channel-get pl)))
>> ; gives same result as above.
>>
>> Any ideas what I'm doing wrong or what I'm missing?
>>
>> Many thanks,
>>
>>
>
>