When I compile your code I get:

$ perl -c   959680.pl
Type of arg 1 to push must be array (not scalar dereference) at 959680
+.pl line 95, near "@list;"
Type of arg 1 to push must be array (not scalar dereference) at 959680
+.pl line 96, near "@callers;"
Type of arg 1 to push must be array (not scalar dereference) at 959680
+.pl line 112, near "@list;"
959680.pl had compilation errors.
[download]

Which refers to these three lines:

     95          push $id, @list;
     96          push $id, @callers;

    112          push $id, @list;
[download]

The first argument to push must be an array.    Perhaps you meant:

     95          push @list, $id;
     96          push @callers, $id;

    112          push @list, $id;
[download]

If I enable warnings I get these messages:

$ perl -Mwarnings -c   959680.pl
Name "main::key" used only once: possible typo at 959680.pl line 232.
Name "main::savestate" used only once: possible typo at 959680.pl line
+ 65.
Name "main::job_list" used only once: possible typo at 959680.pl line 
+123.
Name "main::message" used only once: possible typo at 959680.pl line 6
+3.
959680.pl syntax OK
[download]