Okay. On the basis of the (still scant) specification provided, this is how I would prototype that application. You'll see that I've dodged the issue of the shared hash and locking all together by using a queue:

# perl -slw
use strict;
use Time::HiRes qw[ time sleep ];
use threads;
use threads::shared;
use Thread::Queue;

$|++;

my $SOsem : shared;
sub tprintf { 
    lock $SOsem; 
    printf "[%3d]" . $_[ 0 ], threads->tid, @_[ 1 .. $#_ ]; 
}
sub tprint { 
    lock $SOsem; 
    printf "[%3d] %s" . $/, threads->tid, join ', ', @_; 
}


sub gatherer {
    my $tid = threads->tid;
    my( $Q, $stop, $interval ) = @_;
    while( !$$stop ) {
        ## Get dataset
        my @data :shared = ( $tid, time(), map int( rand 100 ), 1 .. 5
+ );
        $Q->enqueue( \@data );
        sleep $interval;
    }
}

sub sender{
    my $tid = threads->tid;
    my( $Q, $stop, $interval ) = @_;
    while( sleep $interval ) {
        my $available = $Q->pending;
        last if $$stop and !$available;
        next unless $available;
        my @datasets;
        push @datasets, [ @{ $Q->dequeue } ] for 1 .. $available;

        ## 'send' the data
        tprint "\n", time();
        tprint "@$_" for @datasets;
    }
}

our $GATHERERS ||= 5;
our $INTERVAL  ||= 15;
our $GINTERVAL ||= $INTERVAL;

my $Q = new Thread::Queue;
my $stop :shared = 0;
$SIG{ INT } = sub { $stop = 1 };

threads->create( \&gatherer, $Q, \$stop, $GINTERVAL )->detach
    for 1 .. $GATHERERS;

my $sender = threads->create( \&sender, $Q, \$stop, $INTERVAL )->join;
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