Dirty Wordpress APC caching

February 13, 2010 — Florent Clairambault

One or two weeks ago, I made a simple AB benchmarking test on a PHP site I built, it was ok. Then I did the same test on this blog and well… It was freaking slow… On 100 pages with 10 concurrent access, it took 3.5 to 10s to render. Well, I thought I should remove all these plugins I installed to make me and my blog famous (they didn’t perform well). It reduced the generation time by something like 100 ms.

So I had the brilliant idea to put everything in an APC cache, someone had the same idea.

So I approximatively did the same thing :

In the beginning of the index.php file :

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if ( $_SERVER['REQUEST_METHOD'] == 'GET' ) {
 
        // This key will identify the page used
        $cacheKey = 'WP_'.$_SERVER['HTTP_HOST'].md5( $_SERVER['REQUEST_URI'] );
 
        // We try to get this page
        $cacheData = apc_fetch($cacheKey);
 
        // If we got something
        if (is_array( $cacheData )) {
 
                // We give each header
                foreach( $cacheData[0] as $h )
                        header( $h );
 
                // And the content
                die($cacheData[1]);
        }
 
        // If we're still here, we have no cache, so we'll start caching right now
        ob_start();
}

In the end of the index.php file :

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// We have a cache key, it means we have something to cache
if ( $cacheKey )
        apc_store( $cacheKey, array( headers_list(), ob_get_contents() ), 900 );

And once it’s cached it performs well, to make it short it can serve in mean time of 1 ms and gives a general bandwidth of 200 MB/s. As you can guess, these tests are made locally and this is normal.

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[root@s15342968 ~]# ab -n 100  "http://florent.clairambault.fr/"
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
 
Benchmarking florent.clairambault.fr (be patient).....done
 
 
Server Software:        Apache/2.2.8
Server Hostname:        florent.clairambault.fr
Server Port:            80
 
Document Path:          /
Document Length:        161165 bytes
 
Concurrency Level:      1
Time taken for tests:   0.119899 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Total transferred:      16156100 bytes
HTML transferred:       16116500 bytes
Requests per second:    834.04 [#/sec] (mean)
Time per request:       1.199 [ms] (mean)
Time per request:       1.199 [ms] (mean, across all concurrent requests)
Transfer rate:          131585.75 [Kbytes/sec] received
 
Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:     1    1   0.0      1       1
Waiting:        0    0   0.1      0       1
Total:          1    1   0.0      1       1
 
Percentage of the requests served within a certain time (ms)
  50%      1
  66%      1
  75%      1
  80%      1
  90%      1
  95%      1
  98%      1
  99%      1
 100%      1 (longest request)
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[root@s15342968 ~]# ab -n 100 -c 10  "http://florent.clairambault.fr/"
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
 
Benchmarking florent.clairambault.fr (be patient).....done
 
 
Server Software:        Apache/2.2.8
Server Hostname:        florent.clairambault.fr
Server Port:            80
 
Document Path:          /
Document Length:        161165 bytes
 
Concurrency Level:      10
Time taken for tests:   0.47897 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Total transferred:      16156100 bytes
HTML transferred:       16116500 bytes
Requests per second:    2087.81 [#/sec] (mean)
Time per request:       4.790 [ms] (mean)
Time per request:       0.479 [ms] (mean, across all concurrent requests)
Transfer rate:          329394.31 [Kbytes/sec] received
 
Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       0
Processing:     1    4   1.3      4      10
Waiting:        0    1   1.0      1       4
Total:          1    4   1.3      4      10
 
Percentage of the requests served within a certain time (ms)
  50%      4
  66%      4
  75%      5
  80%      5
  90%      6
  95%      6
  98%      8
  99%     10
 100%     10 (longest request)
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[root@s15342968 ~]# ab -n 10000 -c 10  "http://florent.clairambault.fr/"
This is ApacheBench, Version 2.0.40-dev <$Revision: 1.146 $> apache-2.0
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Copyright 2006 The Apache Software Foundation, http://www.apache.org/
 
Benchmarking florent.clairambault.fr (be patient)
Completed 1000 requests
Completed 2000 requests
Completed 3000 requests
Completed 4000 requests
Completed 5000 requests
Completed 6000 requests
Completed 7000 requests
Completed 8000 requests
Completed 9000 requests
Finished 10000 requests
 
 
Server Software:        Apache/2.2.8
Server Hostname:        florent.clairambault.fr
Server Port:            80
 
Document Path:          /
Document Length:        161165 bytes
 
Concurrency Level:      10
Time taken for tests:   7.898135 seconds
Complete requests:      10000
Failed requests:        0
Write errors:           0
Total transferred:      1616094683 bytes
HTML transferred:       1612133495 bytes
Requests per second:    1266.12 [#/sec] (mean)
Time per request:       7.898 [ms] (mean)
Time per request:       0.790 [ms] (mean, across all concurrent requests)
Transfer rate:          199821.47 [Kbytes/sec] received
 
Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.9      0       7
Processing:     2    6   1.6      7      13
Waiting:        0    1   1.4      1       8
Total:          2    7   1.5      7      16
 
Percentage of the requests served within a certain time (ms)
  50%      7
  66%      8
  75%      8
  80%      8
  90%      9
  95%     10
  98%     11
  99%     11
 100%     16 (longest request)

By the way, APC 3.0.x really has a deadlock bug. It totally crashes Apache making it accept but never reply connections. Everyone should update to APC 3.1.

Posted in English. Tags: , , . No Comments »

WordPress supports MultiSites

January 10, 2010 — Florent Clairambault

WordPress now supports MultiSites with its 3.0 version. It’s the current SVN development version. This means you can have one wordpress install for multiple sites. You can see how it works by looking into “ms-settings.php”.

This is quite a good news for anyone willing to manage a community of bloggers.

Here is a part of the wp-includes/wp-settings.php file :

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function wpmu_current_site() {
        global $wpdb, $current_site, $domain, $path, $sites;
        if( defined( 'DOMAIN_CURRENT_SITE' ) && defined( 'PATH_CURRENT_SITE' ) ) {
                $current_site->id = (defined( 'SITE_ID_CURRENT_SITE' ) ? constant('SITE_ID_CURRENT_SITE') : 1);
                $current_site->domain = DOMAIN_CURRENT_SITE;
                $current_site->path   = $path = PATH_CURRENT_SITE;
                if( defined( 'BLOGID_CURRENT_SITE' ) )
                        $current_site->blog_id = BLOGID_CURRENT_SITE;
                return $current_site;
        }
 
        $current_site = wp_cache_get( "current_site", "site-options" );
        if( $current_site )
                return $current_site;
 
        $wpdb->suppress_errors();
        $sites = $wpdb->get_results( "SELECT * FROM $wpdb->site" ); // usually only one site
        if( count( $sites ) == 1 ) {
                $current_site = $sites[0];
                $path = $current_site->path;
                $current_site->blog_id = $wpdb->get_var( "SELECT blog_id FROM {$wpdb->blogs} WHERE domain='{$current_site->domain}' AND path='{$current_site->path}'" );
                $current_site = get_current_site_name( $current_site );
                wp_cache_set( "current_site", $current_site, "site-options" );
                return $current_site;
        }
        $path = substr( $_SERVER[ 'REQUEST_URI' ], 0, 1 + strpos( $_SERVER[ 'REQUEST_URI' ], '/', 1 ) );
        if( is_subdomain_install() ) {
                $current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path = %s", $domain, $path) );
                if( $current_site != null )
                        return $current_site;
                $current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path='/'", $domain) );
                if( $current_site != null ) {
                        $path = '/';
                        return $current_site;
                }
 
                $sitedomain = substr( $domain, 1 + strpos( $domain, '.' ) );
                $current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path = %s", $sitedomain, $path) );
                if( $current_site != null )
                        return $current_site;
                $current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path='/'", $sitedomain) );
                if( $current_site == null && defined( "WP_INSTALLING" ) == false ) {
                        if( count( $sites ) == 1 ) {
                                $current_site = $sites[0];
                                die( "That blog does not exist. Please try <a href='http://{$current_site->domain}{$current_site->path}'>http://{$current_site->domain}{$current_site->path}</a>" );
                        } else {
                                die( "No WPMU site defined on this host. If you are the owner of this site, please check <a href='http://codex.wordpress.org/Debugging_WPMU'>Debugging WPMU</a> for f
urther assistance." );
                        }
                } else {
                        $path = '/';
                }
        } else {
                $current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path = %s", $domain, $path) );
                if( $current_site != null )
                        return $current_site;
                $current_site = $wpdb->get_row( $wpdb->prepare("SELECT * FROM $wpdb->site WHERE domain = %s AND path='/'", $domain) );
                if( $current_site == null && defined( "WP_INSTALLING" ) == false ) {
                        if( count( $sites ) == 1 ) {
                                $current_site = $sites[0];
                                die( "That blog does not exist. Please try <a href='http://{$current_site->domain}{$current_site->path}'>http://{$current_site->domain}{$current_site->path}</a>" );
                        } else {
                                die( "No WPMU site defined on this host. If you are the owner of this site, please check <a href='http://codex.wordpress.org/Debugging_WPMU'>Debugging WPMU</a> for f
urther assistance." );
                        }
                } else {
                        $path = '/';
                }
        }
        return $current_site;
}
Posted in English. Tags: , . No Comments »

WP Codebox Quick fix for Wordpress 2.9

December 7, 2009 — Florent Clairambault

This bug has been fixed !

I like to have the latest version of Wordpress, this is why I use the SVN version. And recently the CSS of the “WP Codebox” plugin stopped working. Here the explanation and the solution :

It seems that starting with the 2.9 version, you can register the styles in the “wp_print_scripts” action method. So in the wp-codebox.php file, you have to put this :

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add_action('wp_print_scripts', 'Codebox_ScriptsAction');
function Codebox_ScriptsAction ()
{
    $cb_path = get_bloginfo('wpurl') . "/wp-content/plugins/wp-codebox"; //URL to the plugin directory
    if (! is_admin()) {
        wp_enqueue_script('jquery');
        wp_enqueue_script('codebox', $cb_path . '/js/codebox.js', array('jquery'), '0.1');
    }
}
 
add_action('wp_print_styles', 'Codebox_StylesAction');
function Codebox_StylesAction() {
        $cb_path = get_bloginfo('wpurl') . "/wp-content/plugins/wp-codebox"; //URL to the plugin directory
        if (! is_admin()) {
                wp_enqueue_style('codebox', $cb_path . '/css/codebox.css', array(), '0.1', 'screen');
        }
}

And it will work…

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