Names "A" and "B" are used for simplicity. I didn't use them in real codes.

The following gives short enough but clear code samples that result in 1 warning and 1 error messages that confused me.

1. "Attempt to free unreferenced scalar" warning.
for simplicity, there are 2 perl script files: test.pl and test.pm.
_test.pl_

use threads;
use test;
 
my $argument=1;
 
my $thread=threads->create("forthread", ($argument));
$thread->join();
exit(0);
[download]

_test.pm_

package test;
 
require Exporter;
                               
our @ISA        =qw(Exporter);
our @EXPORT     =qw(queuereader);
our @VERSION    =1.0;
 
sub forthread{
        my ($arg)=@_;
        return 0;
} #forthread
[download]

NOTE: there is no problem if "forthread" is in test.pl. But when we put "forthread" in a separate file other than the caller file, it reports the above warning message, in fact, no matter if we pass any argument at time of thread creation.

2. "Scalar leaked:1" error.
It is for simplicity that bareword "argument" is used in place of any type of variable.
_test.pl_

use threads;
use test;
 
my $thread=threads->create("forthread", (argument));
$thread->join();
exit(0);
[download]

-test.pm_

package test;
 
require Exporter;
                               
our @ISA        =qw(Exporter);
our @EXPORT     =qw(queuereader);
our @VERSION    =1.0;
 
sub forthread{
        my (argument)=@_;
my $thread=threads->create("another", (argument));
$thread->join();
        return 0;
} #forthread

sub another{
return 0;
} #another
[download]

NOTE: the error is reported when "argument" is one of the following:
- reference to scalar
- reference to array
- reference to hash
- hash

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