Beefy Boxes and Bandwidth Generously Provided by pair Networks
There's more than one way to do things

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

How can I update a global variable across threads as I am getting garbage value for the variable across threads.

Below is sample code which shows the problem

use strict; use warnings; use threads; my $currentWrite = 10; my $totalSize = 1000; sub Progress { my $size = shift; $currentWrite += $size; my $currentProgress = $currentWrite / 100; print "Done ", $currentProgress, " of ", $totalSize, "\n"; } sub test { my $countRef = shift; my $count = $$countRef; Progress ( 11); print "Current count is $count\n"; } Progress(10); my $numThreads = 5; my @arrThreads; for my $i ( 1 .. $numThreads) { my $t = threads->create( \&test, \$i); push( @arrThreads, $t); } foreach (@arrThreads) { my $num = $_->join; }

Below is the output of above program.

# perl Done 0.2 of 1000 Done 0.31 of 1000 Current count is 2 Done 0.31 of 1000 Current count is 1 Done 0.31 of 1000 Current count is 3 Done 0.31 of 1000 Current count is 4 Done 0.31 of 1000 Current count is 5

How to share the data across threads so that the value get updated properly.

In reply to Updating global variable in multi-threaded program by techman2006

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others avoiding work at the Monastery: (4)
As of 2023-12-02 01:57 GMT
Find Nodes?
    Voting Booth?
    What's your preferred 'use VERSION' for new CPAN modules in 2023?

    Results (13 votes). Check out past polls.