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

Kevin,

Thanks again for your time looking into this - hope the dissertation 
edits are going well. :)

Some clarification after I tried it this morning:  Invoking racket (with 
"-W debug", thanks for the tip!) on your hello-world-place.rkt hangs at 
the following:

SPAWNED-PROCESS:2865 (/usr/bin/ssh localhost /usr/local/bin/racket -lm 
racket/place/distributed/launch spawn 7000)
try 0 waiting 1 sec to retry connection to localhost:7000

 From the racket repl I tried the following:

 >(define-values (node pl) (spawn-node-supervise-place-at "localhost" 
#:listen-port 7000 "hello-world-place.rkt" 'hello-world))
 >(*channel-put pl "hello")
 >(*channel-get pl)
; dcgm-type: contract violation
; expected: dcgm?
; context...: ; 
/usr/local/lib/racket/collects/racket/place/distributed.rkt:436:8: loop
; /usr/local/lib/racket/collects/xrepl/xrepl.rkt:1342:0
; /usr/local/lib/racket/collects/racket/private/misc.rkt:87:7

Thanks,

Matthew



On 12/15/2012 10:22 PM, Matthew Eric Bassett wrote:
> Kevin,
>
> Many thanks for your response.
>
> The only significant difference between your code and mine is the use 
> of localhost (which makes distributed places a lot less distributed) 
> and the port specification.  In any case, I've tried your code 
> verbatim on two machines now.  It also throws the same dcgm contract 
> violation.
>
> What OS are you running?  Perhaps there's something funny about my 
> build?  I don't know anything about distributed/places internals here, 
> I'm just guessing.
>
> I've tested this on Fedora 17 x64, and on an amazon stock x64 ec2 
> machine.
>
> Regards,
>
> Matthew Eric
>
> On 12/15/2012 04:05 AM, Kevin Tew wrote:
>> 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,
>>>>
>>>>
>>>
>>>
>>
>
>


-- 
Matthew Eric Bassett |http://mebassett.info