while ( $line = <> )

##</code><code>##

use Data::Dumper;

sub process_record
{
	my $record = join q[], @{+shift};
	
	warn "Malformed record: $record"
		unless $record =~ /^ \[ (.+?) \] \s+ \[ (.+?) \] \s+ (.+) $/xs;
	
	local $Data::Dumper::Terse = 1;
	print "Got record ", Dumper +{
		datetime   => $1,
		status     => $2,
		info       => $3,
	};
}

my $current_record;
while (<DATA>)
{
	# we have hit a new record
	if (/^ \[ \d{4}-\d{2}-\d{2} /x)
	{
		process_record($current_record) if $current_record;
		$current_record = []; # start a new record
	}
	push @$current_record, $_;
}
# don't forget to process the final record
process_record($current_record) if $current_record;

__DATA__
[2012-09-14 16:55:22,498] [ACTIVE] INFO - this is a single line
[2012-09-14 16:55:22,498] [ACTIVE] INFO - this
is
a
multi
line
record
[2012-09-14 16:55:22,500] [ACTIVE] INFO - this is another single line
[2012-09-14 16:55:22,500] [ACTIVE] INFO - this is yet single line
[2012-09-14 16:55:22,500] [ACTIVE] INFO - this one is
on two lines
[2012-09-14 16:55:22,500] [ACTIVE] INFO - one last record