devel.kostdoktorn.se » plugins

Plugin for simpler performance profiling

Johan Eenfeldt — Sat, 24 Oct 2009 18:22:51 +0000

How time is spent on a compex page

The two areas where performance problems with WordPress plugins are most common are custom filters/actions and database queries. WP-Profile is a plugin that helps you find such problems.

Actions and filters

WordPress has an intricate system of actions and filters which is used all over the place: to convert : ) into , to make links clickable and to handle the login procedure are just some examples.

Every action and filter is a hook that allows plugins to call custom functions and easily change or override default behavior. That is very useful.

It also makes it easy to really ruin performance as some common filters are called a hundred times or more for more complex pages, making small inefficiencies add up really quickly.

Unfortunately there are no good ways to keep track of the performance impact of individual filters. It is possible to profile the whole system using for example XDebug and *Cachegrind like I did in an earlier post but it is a lot of work and often overkill during plugin development.

Database queries

Database queries in stock WordPress are highly optimized. So much so that they usually only takes a few percent of total time. It is, however, very easy to change this and even seemingly simple queries can take surprisingly long time. By defining SAVEQUERIES in wp-config.php WordPress will record all queries and how long they took to execute in $wpdb->queries.

WP-Profile

WP-Profile is a small plugin I’ve written to use when developing plugins and modifying WordPress. It keeps track of all calls to actions/filters and presents it in an accessible fashion together with query information collected through SAVEQUERIES. It requires that you are comfortable making minor changes to core WordPress files to set up. It is for testing only. You can download it here.

This is the result on stock WordPress for a rather complex page with a lot of comments. Sort tables by clicking on table header (thanks to JQuery TableSorter):

Time (seconds)

% of Total

Calls

Function

Actions / Filters

0.042

12.3%

246

wptexturize

Time (seconds)	% of Total	Calls	Action / Filter
0.022	6.3%	1	the_content
0.008	2.2%	115	the_title
0.007	2.1%	37	comment_text
0.005	1.4%	79	list_cats
<0.001	0.3%	14	bloginfo, link_name, link_description

0.023

6.5%

wpautop

Time (seconds)	% of Total	Calls	Action / Filter
0.013	3.7%	1	the_content
0.01	2.9%	37	comment_text

0.017

4.9%

convert_smilies

Time (seconds)	% of Total	Calls	Action / Filter
0.009	2.6%	1	the_content
0.008	2.3%	37	comment_text

0.01

167

convert_chars

Time (seconds)	% of Total	Calls	Action / Filter
0.004	1.2%	115	the_title
0.003	0.8%	37	comment_text
0.003	0.8%	1	the_content
<0.001	0.1%	14	link_name, link_description, bloginfo

0.007

do_shortcode

the_content

0.007

make_clickable

comment_text

0.006

1.8%

WP_Embed :: run_shortcode

the_content

0.004

1.2%

wp_cron

sanitize_comment_cookies

0.002

0.7%

wp_widgets_init

init

0.002

0.6%

profile_enqueue_requirements

init

0.002

0.5%

wp_filter_kses

Time (seconds)	% of Total	Calls	Action / Filter
0.001	0.3%	5	link_description
0.001	0.3%	5	link_name

0.002

0.5%

WP_Widget_Factory :: _register_widgets

widgets_init

0.001

0.4%

force_balance_tags

comment_text

0.001

0.4%

204

_config_wp_home

option_home

0.001

0.4%

wp_default_scripts

0.001

0.2%

wp_print_head_scripts

wp_head

0.001

0.2%

feed_links_extra

wp_head

0.001

0.2%

kb_filter_avatar

get_avatar

0.135s

39.2%

1071

Time (seconds)	% of Total	Function	Query
0.002	0.6%	comments_template	SELECT * FROM wp_comments WHERE comment_post_ID = 144 AND (comment_approved = ’1′ OR ( user_id = 111 AND comment_approved = ’0′ ) ) ORDER BY comment_date_gmt
0.001	0.4%	get_pages	SELECT * FROM wp_posts WHERE (post_type = ‘page’ AND post_status = ‘publish’) ORDER BY menu_order, post_title ASC
0.001	0.4%	update_meta_cache	SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN (144)
0.001	0.2%	_fill_user	SELECT meta_key, meta_value FROM wp_usermeta WHERE user_id = 111
0.001	0.2%	get_bookmarks	SELECT * , IF (DATE_ADD(link_updated, INTERVAL 120 MINUTE) >= NOW(), 1,0) as recently_updated FROM wp_links INNER JOIN wp_term_relationships AS tr ON (wp_links.link_id = tr.object_id) INNER JOIN wp_term_taxonomy as tt ON tt.term_taxonomy_id = tr.term_taxonomy_id WHERE 1=1 AND link_visible = ‘Y’ AND ( tt.term_id = 2 ) AND taxonomy = ‘link_category’ ORDER BY link_name ASC
0.01s	2.9%

Cache Translation Object v1.2

Johan Eenfeldt — Fri, 23 Oct 2009 11:07:17 +0000

Another new version of Cache Translation Object plugin released.

We need to whitelist which get_locale() calls we filter: load_plugin_textdomain() yes, get_bloginfo() no.

For the future I’m hoping to get a new filter to use.

Cache Translation Object v1.1

Johan Eenfeldt — Thu, 22 Oct 2009 23:38:45 +0000

New version of Cache Translation Object plugin released.

The major focus of this release is to handle multi-locale correctly — for example if you have one of the multi-language plugins, or if you use different languages on different installations on same host.

This was actually quite a bit of work to get working correctly for Shared Memory. Shared Memory objects doesn’t actually get deleted until every reference to the object is closed, from potentially multiple concurrent page load.

Change Log

Version 1.1

Rewritten to cache multiple locales separately
Split out admin functions into separate file
Handle old SHM with questionable delete behaviour by relocating as necessary.
Add storage debug info link
Do not default to any specific storage type, make user choose
Tell admin when something is wrong (also better error handling).
Added plugin localization
Added Swedish translation

The WordPress Localization Performance Battle

Johan Eenfeldt — Fri, 16 Oct 2009 11:22:27 +0000

Using WordPress translated to your own language results in a surprisingly large performance cost. In my tests it took twice (or four times!) as long for an unmodified WordPress 2.8.4 start page to load when using a localized WordPress.

Translating a lot of text in an user friendly fashion is hard to do efficiently.

But there are things we can do to make it a lot less painful. Most of the time is actually spent when WordPress reads the MO files containing all text to translate and structures it into the l10n object to prepare for the translations to come. On each page load.

The obvious solution is to cache the resulting object. So I did.

Limit Login Attempts 2.0beta3

Johan Eenfeldt — Sat, 10 Oct 2009 18:07:53 +0000

Consider trying this beta version of the Limit Login Attempts plugin– it should be more or less finished. Please post any problems (or successes).

The major focus of this new version is to protect the user login names of privileged users from discovery. Which, it turns out, is a lot of work to do correctly.

It includes optional restrictions on password reset attempts and new user registrations. The plugin also helps you see and modify the various names WordPress keep for each user. By default WordPress uses the user login name to construct author archive URLs, nickname, displayname and so on.

It also allows you to change the URL name of users. I actually find it rather strange that there is no way to change it in stock WordPress.

Remaining on the todo list: Translations, the readme.txt, some documentation, and some further testing.

Screenshots of new settings: 2.8.4, 2.5

Faster Smilies

Johan Eenfeldt — Sat, 10 Oct 2009 17:52:58 +0000

A Deprecated WordPress Plugin.

When working on profiling a WordPress install I found, to my surprice that for a 400 comment post the single most expensive thing was translating smilies to pictures — 55% of time to create the page!

Apart from sending a patch fixing this (which went into WordPress 2.8) I also made a small plugin to use before the new version was available.

It is no longer useful as everyone should be using a modern WordPress version.

It can be found here.

Limit Login Attempts 2.0beta2

Johan Eenfeldt — Sat, 03 Oct 2009 23:02:21 +0000

Consider trying this beta version. Please post any problems (or successes).

The major focus of this new version is to hide the username of privileged users. Which, it turns out, is a lot of work to do correctly.

It includes optional restrictions on password reset attempts and new user registrations. It also lists any privileged users whose username as the various names displayed on the blog. Which by default is all of them as WordPress default uses the username to construct author archive URLs, among other things.

Largest missing piece is functionality to modify username (which might possibly be dangerous to do) and “nicename” (which might invalidate previous author archive URLs).