Manual:Ajust del rendiment

This page described how to improve the performance of your MediaWiki install.

MediaWiki is capable of scaling to meet the needs of large wiki farms such as those of Wikimedia Foundation, WikiHow, and Fandom; and can take advantage of multiple load-balanced database servers, Memcached object caching, Varnish caches (see Manual:Varnish caching ), and multiple application web servers.

For most smaller installations, doing everything on this page is overkill. Start with making sure you have PHP OPcache enabled, PHP APCu installed , and enable the "main cache" in MediaWiki.

Quick start

Short version: We recommend bytecode cache for PHP, APCu as local server cache, and Memcached for main cache. This is what the Wikimedia Foundation uses for Wikipedia in production.

Puppet manifest

If you happen to manage your server with Puppet, you can apply some of these tips automatically. Most of the tweaks on this page have been collected in a puppet manifest (puppet/modules/role/manifests/simple_performant.pp and puppet/modules/role/manifests/simple_miser.pp).

PHP

Bytecode caching

OPcache improves MediaWiki performance by removing the need for PHP to load and compile scripts on every request.

See also: PHP configuration#Opcode caching

PHP works by compiling a PHP files to bytecode, and then executing that bytecode. When compiling a large application such as MediaWiki, this takes time. OPcache works by reusing previously compiled bytecode, and executing it directly. This avoids spending time to compile the same code on every request. OPcache was introduced in PHP 5.5.0 (Compatibility § PHP).

There is no MediaWiki configuration required to use OPcache. Once PHP OPcache is installed and enabled on your server, it "just works".

LuaSandbox

If you use Extensió:Scribunto , be sure to install LuaSandbox , which is faster than the default LuaStandalone engine.

Object caching

For how to use caching as a developer in MediaWiki core or an extension, see Object cache .

Local server

The local server cache is used for lightweight caching directly on the web server.

To enable it, install PHP APCu. Prior to MediaWiki 1.42, WinCache was supported as well.

Once installed, MediaWiki automatically detects and uses the local server cache. No MediaWiki configuration necessary.

To install APCu on Debian and its derivatives, use:

sudo apt-get install php-apcu php-igbinary

A script, apc.php is bundled with the APCu package which can be used to inspect the status of the cache, and also examine the contents of the user cache to verify that MediaWiki is correctly using it.

Main cache

The main cache can be used by MediaWiki to reuse results of larger or more expensive computations.

Main cache (recommended)

The main cache is disabled by default. To enable it, follow instructions from the Memcached or Redis page.

Alternatively, you can define custom backends via $wgObjectCaches and set $wgMainCacheType to a key in $wgObjectCaches.

If your MediaWiki installation is served from multiple web servers, then your web servers must refer to the same cache server(s). You must not use APCu as your main cache if you have multiple web servers. Having each web server use its own separate main cache would cause stale values, corruption, and other unexpected side-effects. Note that for lightweight values (the "local server cache"), MediaWiki will still automatically and correctly use of APCu regardless of any $wgMainCacheType setting.

Main cache (basic)

If you operate a small wiki from a single web server and prefer not to install an external service like Memcached or Redis, and you do have APCu installed, then you can APCu as your main cache as well by setting the following in LocalSettings.php . By default, the user session store ($wgSessionCacheType ) and parser output cache ($wgParserCacheType ) inherit the MainCacheType. When using APCu as your main cache, it is recommended to override these in favor of the database. See task T147161 for more info.

$wgMainCacheType = CACHE_ACCEL;
$wgSessionCacheType = CACHE_DB;
$wgParserCacheType = CACHE_DB;

While installing Memcached is more complicated, it is very effective and recommended.

Interwiki cache

MediaWiki interwiki prefixes are stored in the interwiki database table. See Interwiki cache for how to enable caching.

Localisation cache

By default, interface message translations are cached in the l10n_cache database table. Ensure $wgCacheDirectory in LocalSettings.php is set to a valid path to use a local caching instead. See Help:System message#Caching for more details.

Sidebar cache

A small save in DB queries can be obtained by caching the sidebar (disabled by default). See $wgEnableSidebarCache and $wgSidebarCacheExpiry .

Page view caching

Page view caching increases performance tremendously for anonymous (not logged-in) users. It does not affect performance for logged-in users.

Caching proxy

A caching proxy (or "HTTP accelerator") stores a copy of web pages generated by your web server. When such page is requested a second time, then the proxy serves up its local copy, instead of passing the request onto the real web server.

This massively improves the response times for page loads by end users, and also tremendously reduces the computational load on the MediaWiki web server. When a page is edited, MediaWiki can automatically purge the local copy from the cache proxy.

Examples of cache proxies:

• Varnish Cache, this is currently (as of November 2018) used by Wikipedia. See also Manual:Varnish caching .
• Nginx's FastCGI module can cache PHP responses; see: Manual:Nginx caching
• Squid, this was used by Wikipedia prior to 2012.
• Apache's mod_cache_disk, see this article for instructions with MediaWiki.
• Manual:Cloudflare

File cache

See Manual:File cache for main article about this.

In absence of a caching proxy or HTTP accelerator, MediaWiki can optionally use the file system to store the output of rendered pages. For larger sites, using an external cache like Varnish is preferable to using the file cache.

Web server

• if you use Apache as web server, use PHP-FPM, not mod_php. PHP-FPM optimizes re-use of PHP processes.
  • switch Apache to use the event MPM instead of the prefork MPM.
• adjust robots.txt to disallow bots from crawling history pages. This decreases general server load. See Manual:robots.txt .
• HTTP/2 protocol can help, even with ResourceLoader.

Configuration settings

Large sites running MediaWiki 1.6 or later should set $wgJobRunRate to a low number, say 0.01. See Manual:Job queue for more information.

Composer

This will provide no benefit if you enable opcache in PHP.

MediaWiki uses composer for organizing library dependencies. By default these are included from the /vendor directory using a dynamic autoloader. This autoloader needs to search directories which can be slow. It is recommended to generate a static autoloader with Composer, which will make your wiki respond faster.

Using a static autoloader is the default for all MediaWiki installations from the tarball download or from Git. If for some reason this is not the case, use the following to generate the static autoloader:

composer update -o --no-dev

Remember that this will need to be re-run after each MediaWiki update as it includes a static copy of which libraries and classes exist in the software.

Limiting requests

One common performance issue is allowing too much concurrency in the webserver. If this happens, various PHP threads can become starved for resources and make no progress. Even worse, they can begin to pile up and not complete even after the user has given up on the page loading causing everything to slow to a crawl. Sometimes its better to do a small number of requests at a time making the other requests wait instead of doing all the requests concurrently.

• Set PHP's memory_limit to an appropriate value (256MB is a common choice)
• Calculate how much RAM you can dedicate to PHP processes. Divide that by the memory_limit for PHP. That is the most web server/php threads you should have running at one time. Keep in mind if you have other things running on the same server such as MySQL or Elasticsearch, they also need RAM.
• Configure your webserver to only allow that many threads. If using Varnish you can use .max_connections, .wait_limit and .wait_timeout to control the number of concurrent backend requests. If using Apache without Varnish, set MaxRequestWorkers
  • If using Varnish you can setup multiple backends with different max connections to prioritize different types of users.
• Install Excimer and set $wgRequestTimeLimit to a reasonable value (e.g. 300). This will ensure that MediaWiki terminates the request if it gets stuck.
• If using MariaDB and only using the server for MediaWiki, consider setting max_statement_time in your server .ini file to a value of about 200. This will force any DB query from taking more than 200 seconds. Just remember to remove it before running Update.php .

Database configuration

MySQL

For a heavy concurrent write load, InnoDB is essential. Use memcached, not the default MySQL-based object cache.

See below for some DB configuration tricks. You can also try and run the mysql-tuning-primer script to get some quick statistics and suggestions.

Multiple servers

The database software and web server software will start to fight over RAM on busy MediaWiki installations that are hosted on a single server. If your wiki has a consistent traffic, a logical step, once other performance optimizations have been made (and cache serves most of the content), is to put the database and web server on separate servers (or, in some cases, multiple separate servers, starting with a replica.) Also:

• check that MySQL has query cache enabled and enough memory; (This advice is controversial, be sure to test if it actually improves things in your setup. In some cases it can slow things down)
• give most memory to innodb_buffer_pool;
• add cores for MySQL if maxed out at peak times;
• give memcached even more RAM for in-memory cache.
• Make sure max_heap_table_size, tmp_table_size, and tmp_memory_table_size are appropriately large, especially if using extensions that provide querying functionality like SemanticMediaWiki

Benchmarking

Some tools can help quickly evaluate the effects of performance tuning.

• http://webpagetest.org is "real life" testing, commanded in your browser.
• ab is a command line tool which quickly produces some nice stats.
• PageSpeed

See also

• More extensive changes, sacrificing some functionality
  • How to make MediaWiki fast
• For developers:
  • Logging and Manual:Profiling
  • North's Performance chapter
• Wikimedia Foundation-specific documentation:
  • Backend performance guide of the Wikimedia Performance Team
  • Frontend performance guide of the Wikimedia Performance Team

References