Greetings kixsnap and welcome to the Monastery. I bring you glad tidings of great joy for all mankind.

Yes, you can use Selenium::Remote::Driver in a parallel application. One of the more convoluted small helper apps I have built was a program that ran continuously offline looping through records from a DB and making a series of calls for each using S::R::D and Firefox. The program had been running for several months when I left that assignment.

Things that might be different between my environment then and yours:

• I was not using threads (and never have), although the solution I implemented would work under a threading environment as far as I know.
• I was running on a Unix server with no GUI, so I used a set of X window emulators as large as the number of worker processes for the Firefox instances to operate in. I ran a daemon to make sure the emulators were always available.
• Firefox may have changed since then (~ 4-5 years ago); I haven't done any web client automation work since then so I don't know.
• I was using the magnificent and mighty MCE (MCE::Loop back then; now I would most likely use MCE::Flow...) and MCE::Shared. The code presented below is mostly a redacted version of what I built back then; please bear in mind that there may be some naive MCE idioms there; do your own reading to find out the state of the MCE and MCE::Shared art nowadays.

=pod

#  $ DISPLAY=:99 perl script.pl

You need to set the C<DISPLAY> env variable because this script uses h
+eadless
Firefox instances run by Selenium.

=cut

use strict; use warnings;
use MCE::Shared;
use MCE::Loop;
use Tie::Cycle;

my $pid = $$;

END { report() if $$ == $pid }
# only parent process reports results

# Overall results hash, shared between processes
my $results = MCE::Shared->hash();

# Process the data

my %data = get_data(); # in this case, was keyed by HTTP method

for my $method ( keys %data ) {
    MCE::Loop->init( chunk_size => 100, max_workers => 8 );

    tie my $screen, 'MCE::Shared', { module => 'Tie::Cycle' }, [ 0 .. 
+7 ];
    # We have a fixed number of screens in our virtual X buffer;
    # this range should match the number of MCE worker processes

    mce_loop {
        my ( $mce, $chunk_ref, $chunk_id ) = @_;

        my $driver = get_selenium_driver();
        # or maybe an obj that already knows what SRD commands to run
        
        # Set the screen ID for a Firefox instance (for Selenium)
        $ENV{'DISPLAY'} = ':99.' . $screen;

        for ( @{ $chunk_ref } ) {
            my %this_job_data = %{ $_ };

            if ( $this_job_data{skip} ) {
                $results->incr('SKIP');
                next;
            }

            $driver->do_the_thing( $this_job_data );
            
            $results->incr('OK');
            $results->incr($this_job_data->{something});
        }
    } @{ $data{ $method } };

    MCE::Loop->finish;
}

##
sub report {
    # do something with $results
}

__END__
[download]

Hope this helps!