Hello,

I am running an Apache/2.2.17 (Ubuntu) with mod_perl 2.0 and Perl version 5.10.1. I created a module CitySearcher.pm that has a handler method to handle the request from the browser. The module has roughly the following format (simplified): 

package CitySearcher;

use strict;

...
use Tree::Trie;
use threads::shared;
use APR::OS;

my $TRIE :shared;
my $TRIE_LOCK :shared = {};

sub handler {
    my $r = shift;
    $r->content_type('text/html');
    
    ...
    
    my $request = new CGI;
    my $tid = APR::OS::current_thread_id();
    lock($TRIE_LOCK);
    if(!defined($TRIE)) {
        print stream "$$-$tid: creating trie\n";
        my $trie = new Tree::Trie;
        ...
        #populate $trie
        ...        
        $TRIE = shared_clone($trie);
    }
    
    print stream "$$-$tid: returning trie\n";
    
    ...
    #use trie
    ...

    return Apache2::Const::OK;
}

1;

[download]

Then I restart the server and pound the server with about 25 calls within milliseconds to the page. Here is the ouput from the stream: 

10320-3056253808: creating trie
10320-3056253808: returning trie
10320-3064646512: returning trie
10320-3056253808: returning trie
10320-3064646512: returning trie
10320-3064646512: returning trie
10320-3056253808: returning trie
10320-3064646512: returning trie
10320-3056253808: returning trie
10320-3064646512: returning trie
10320-3064646512: returning trie
10320-3022682992: creating trie
10320-3022682992: returning trie
10320-3047861104: creating trie
10320-3047861104: returning trie
10320-3056253808: returning trie
10320-3056253808: returning trie
10320-3022682992: returning trie
10320-3064646512: returning trie
10320-3031075696: creating trie
10320-3031075696: returning trie
10320-3064646512: returning trie
10320-3022682992: returning trie
10320-3056253808: returning trie
10320-3056253808: returning trie
10320-3039468400: creating trie
10320-3039468400: returning trie
10320-3022682992: returning trie
10320-3064646512: returning trie
10320-3056253808: returning trie

[download]

As you can see, thread 3056253808 initially creates the trie and then thread 3064646512 uses it too (no creating trie output). A little bit later thread 3022682992 comes along and creates a trie again. Why was the trie not shared? All threads are clearly running in the same process.

Thank you very much for your help.

Sincerely,

Pawel

SOLVED (I think):

I removed PerlInitHandler Apache2::Reload from my Apache configuration. Looks like the shared variables are removed when the Apache2::Reload module does its thing. I hope this tip helps anyone with a similar problem in the future.

In reply to On Apache server using mod_perl shared_clone does not produce shared object by busymeister

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


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.