#! perl -slw
use strict;
use threads;
use threads::shared;
use DBI;

##### Warning: entirely untested code ##############

our $THREADS ||= 5;

## A shared 'semaphore'
## This works fine in single cpu boxes
## but may need to be replaced with a 'proper' semaphore 
## on multi-cpu machines
my $running : shared = 0; 

sub worker {
	$running++;
	
	## get a new handle to the DB in each thread
	my $dbh = DBI->connect(...);
	my $sth = $dbh->prepare(
		"INSERT INTO T_$filename ("
		. join( ', ', @column )
		. ") VALUES ("
		. join( ',', ( '?' ) x @column )
		.")"
	);

	## get a handle to the CSV file for this thread
	my $fileno = shift;
	open my $fh, "<&=$fileno" or die $!;

	## process the data
	## batching would be of little benefit 
	## if you're going to read a batch
	## and then execute them individually
	while( <$fh> ) {
		$sth->execute( split ',', $_ );
	}
	$dbh->disconnect;
	$running--;
}

my $fh;
## Open the file in root 
open $fh, 'file.csv' or die $!;

## and then 'share' it with the worker threads by passing the fileno
threads->create( \&worker, fileno( $fh ) )->detach for 1 .. $THREADS;

sleep 1 while $running < $THREADS; ## Let'em start
sleep 1 while $running; ## Wait for'em to finish