in reply to YASWI "Prolog System Error: Thread 1"

sub set_location_list{
    ...
    my @files = (t("/home/steve/Documents/i_prolog.pl"));
    swi_init("pl", "-g", "true", "-nosignals"); # Or swi_init("-nosign
+als");
    swi_consult @files;
    ...
}

[download]
Try moving swi_init(...) outside of the sub in order to get it executed just once.

I've also tried swi_cleanup() after every Prolog call.

swi_cleanup() is not fully implemented by the SWI-Prolog engine (though the error you are getting probably indicates a bug in L::P::Yaswi) so its usage should be avoided.

File a bug report on the CPAN RT site including a minimal script that triggers it (both perl and prolog code), your OS, Perl and Prolog versions and compilation options and any other pertinent details about your environment (for instance, if you are running it under mod_perl).

I would try to reproduce and solve any error.

Replies are listed 'Best First'.
Re^2: YASWI "Prolog System Error: Thread 1"
by Steve_BZ (Chaplain) on Jan 19, 2010 at 15:02 UTC

    Hi Salva

    Thanks for this, I'll try it out. Do you prefer:

    swi_init("pl", "-g", "true", "-nosignals");

    or 

    swi_init("-nosignals");

    [download]

    regards

    Steve

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      IIRC, the right combination is... 
      swi_init(qw(-nosignals -g true))

      [download]
      The -g true part serves to silence the welcome banner generated by default by the Prolog engine.
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Re^2: YASWI "Prolog System Error: Thread 1"
by Steve_BZ (Chaplain) on Jan 20, 2010 at 14:42 UTC

    Hi Salva

    Well after a few version control problems of my own making, we're back to a stable system.

    I've implemented the line you suggest at the beginning of the module (.pm file). However, I'm not sure that it's the optimum way. This is what it looks like now:

    updated

    #!/usr/bin/perl -w
use strict;

package i_observation;
######################delete block ##########################

use Wx 0.15 qw[:allclasses];
use strict;
use warnings;
use Wx qw[:everything];
use Wx::Event qw( EVT_MENU );
use base qw(Wx::Frame);
use threads ();                                        # Used for mult
+i-tasking ffmpeg
use Threads;                                        # Used in Timer to
+ determine state of tasks

use base qw(Wx::Panel Class::Accessor::Fast);
__PACKAGE__->mk_ro_accessors( qw(html_help chm_help comboctrl) );


   
use Language::Prolog::Yaswi qw(:load :run :query);
use Language::Prolog::Types::overload;
use Language::Prolog::Sugar
    functors => {location_organ => 'location_organ',
            location_segment => 'location_segment',
            listsegments => 'listsegments',
            listwalls => 'listwalls',
            diagnosis => 'diagnosis' },
    chains => { orn => ';',
            andn => ',',
            add => '+' },
    vars => [qw (X Y Z)];
swi_init(qw(-nosignals -g true));

sub new{
.
.
.
#  other routines in the package
.
.
.
sub set_location_list{
    
.
.
.
.

    my @files = (t("/home/steve/Documents/i_prolog.pl"));
    swi_consult @files;
      

.
.
.
}

    [download]

    So, it's not clear to me when the code before any routines gets executed. The error now is:

    % /home/steve/Documents/i_prolog.pl compiled 0.00 sec, 32,784 bytes
% /home/steve/Documents/i_prolog.pl compiled 0.00 sec, 0 bytes
% /home/steve/Documents/i_prolog.pl compiled 0.00 sec, -232 bytes

    [download]

    So it looks as though it is called three times. UPDATE: Actually these messages come way before the crash now. There is no crash message at all, so I need to step through the code and find the crash. It may not be Prolog related. Sorry for the confusion.

    Regards

    Steve

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      So, it's not clear to me when the code before any routines gets executed. The error now is: 
      % /home/steve/Documents/i_prolog.pl compiled 0.00 sec, 32,784 bytes

      [download]

      This is not an error, just a message telling you the Prolog module i_prolog.pl has been loaded. If you get it several times it is probably because you are calling set_location_list() repeatedly.

      Without seeing the full source code of your application I can only guess, and maybe there are some real bugs on the module annoying you, but it seems to me that the actual problem is that you don't got it yet. You should become more familiar with the module and Prolog and how they work together before trying to use them inside a complex application.

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        Hi Salva,

        It's true I am.

        Can I just clarify something? Whan I *first* call prolog, the prolog engine is loaded in a second thread, so I don't need to consult the file again. Once i_prolog.pl is loaded, it stays loaded and the engine stays running until the application ends? Is that right? I had been assuming that once I exited the module all the variables cleared themselves, because thgey were out of scope. I get the feeling that this is not true. So the only reason for calling consult @files again is if the files change for any reason, eg if I dynamically alter i_prolog.pl. Have I got that right?

        Thanks for your patient and expert help, it's truly invaluable.

        Regards

        Steve

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