use threads;
use threads::shared;
my %CallInfoHash : shared = ();

my $processToFork = 5;
my $threads = 100;
my %threadsHash;

for ($jj = 0; $jj <  $processToFork; $jj++) {
...fork a process here:
for ($ii = 0; $ii <  $threads; $jj++) {
my $callNum = $jj;
$UrlToDownload = <Some URL>;
push (@argList, $callNum );
push (@argList, $UrlToDownload);
$threadsHash{$CallNumber} = threads->create(\&tsub, @argList);
}
}

sub tsub {
.. Here some operations are done and values are generated.
These values are to be stored in %CallInfoHash  Hash.
my $value1 = xx;
my $value2 = xx;
$CallInfoHash{$CallNumber}{'value1'} = $value1;
$CallInfoHash{$CallNumber}{'value2'} = $value2;
.... There are about 10 values.
}