Re: [Caml-list] mysterious cgi problem

[Mark Shinwell <mshinwell@janestreet.com>]

Is the OCaml executable compiled to native code?

If so, you may be able to trap this by having the HTTP server execute
gdb with commands to execute your OCaml program, and then give you a
backtrace immediately before it exits.  Ensure your program was
compiled with the -g option to ocamlopt.  Then for example if you
currently run:

/my/executable --foo-bar

you would instead run:

gdb -ex "b exit" -ex "r" -ex "bt" -ex "set confirm 0" -ex "q" --args
/my/executable --foo-bar

Mark

On 20 June 2014 06:48, Siraaj Khandkar <siraaj@khandkar.net> wrote:
> Not_found must be coming from some initialization procedure in module Y,
> so try to trap it from there.
>
>
> On 06/19/2014 11:41 PM, Eliot Handelman wrote:
>> Hi list,
>>
>> We have a demo coming up on Monday of an ocaml based music analysis and
>> generation system with a
>> web component for music notation that, irritatingly, has stopped
>> working. The interface is a CGI
>> with an ocaml 4.01 executable. After several harrowing days I narrowed
>> the problem down to the
>> following situation:
>>
>> X, a basic system, runs fine in firefox/chrome/various linuxen
>>
>> X + module Y  generates "Not_found" exceptions in the CGI merely by
>> linking Y. Y is
>> otherwise not invoked.  Moreover, I'm unable to trap the exception in
>> the CGI itself
>> (ie, a try/with around the main function is somehow bypassed as the
>> apache error long reports).  So
>> it would seem the that the code fails before the main function is executed.
>>
>> We were using ocamlnet, but I rolled my own cgi parser and reproduced
>> the problem.
>>
>> Any suggestions? My next step would be to start rolling back the system,
>> which is
>> not pleasant.
>>
>>
>> thanks,
>>
>> -- eliot
>>
>
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