CODEWITHSUNDEEP
multithreadingperlshared-memory
Stanimirovv
Stanimirovv

Reputation: 3172

Perl sharing variables between threads compilation error

I think i shouldn't be getting this error, but since I am getting it, I am obviously wrong. The situation is very simple: Share one variable between N threads and have them increment it by one.

The code is pretty short and straight forward:

use threads;
use threads::shared;
use strict;

sub Handler()
{
    my $shared_var : shared = 1000;
    my @threads; 
    push @threads, thread->new(\&PrintGreeting);
    $_->join for @threads;
}

sub PrintGreeting()
{
    $shared_var++;
    print "hello, world $shared_var \n";
}

Handler();

The error I am getting is:

Global symbol "$shared_var" requires explicit package name at /home/path/tosource/program.pl line 15.

Line 15 is the line where I increment the variable.

I searched, but I couldn't find someone with the same error.

Upvotes: 0

Views: 148

Answers (1)

Richard Huxton
Richard Huxton

Reputation: 22893

Just because you are using threads doesn't mean the rest of Perl's rules are thrown out of the window.

You define my $shared_var in Handler but try to use it in PrintGreeting. That wouldn't work with a normal variable and it won't work with one shared between threads either. Basic variable scoping.

Perhaps you meant to decalre a package-level (global) variable instead?

Upvotes: 1

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