Are these two code different - multithreading

Question

foreach $thr (1..5)
{
$threads[$thr]=threads->create("worker");
}
and
foreach (1..5)
{
push #threads,threads->create("worker");
}
the latter works well, well the former gives warning.
#!/usr/bin/perl
use strict;
use threads;
use threads::shared;
use Thread::Queue;
my $queue = Thread::Queue->new();
my #threads;
my $thr;
#----------------------------------------create
#send work first,and then creat threads, the first thread work earlier.
$queue->enqueue(1..10000);
foreach (1..5)
{
push #threads,threads->create("worker");
}
$queue->end();
sub worker
{
while (my #DataElement = $queue->dequeue(100))
{
my $tid = threads->tid();
#open (my $out,">>$tid.txt") or die $!;
print "Threads ID:$tid\t#DataElement\n";
#print $out "Threads ID:$tid\t#DataElement\n";
#close $out;
}
}
#----------------------------------------cut
my $thr_num=1;
my $i;
while ($thr_num)
{
$i++;
foreach (#threads) #store threads, TRUE even if joined.
{
$thr_num = threads->list();
print "threads total: $thr_num\n";
if ($_->is_running())
{
sleep 1; #wait
next;
}
if ($_->is_joinable())
{
$_->join();
}
sleep 1;# wait
}
print $i,"\n";
}
this is the whole code. and the warning is can't call method "is_running" on an undefined value at threadqueue2(1).plx.line42. Perl exited with active threads.

Answer 1

No. You will end up with different data structures. As you can see from this simplified version of your code.
#!/usr/bin/perl
use strict;
use warnings;
use 5.010;
use Data::Dumper;
my #threads;
foreach my $thr (1 .. 5) {
$threads[$thr] = 'A Thread';
}
say Dumper \#threads;
#threads = ();
foreach (1 .. 5) {
push #threads, 'A Thread';
}
say Dumper \#threads;
The output is:
$VAR1 = [
undef,
'A Thread',
'A Thread',
'A Thread',
'A Thread',
'A Thread'
];
$VAR1 = [
'A Thread',
'A Thread',
'A Thread',
'A Thread',
'A Thread'
];
In your first example, you begin populating the array at element 1, so the first element (which has an index of 0) contains undef.