Performance

Here are some tips to increase XWiki's performance.

Gzip compression and caching of static pages

We're working on making these features part of the XWiki core (see XWIKI-2022). While waiting for this to be natively implemented, the recommended solution is to set up an Apache Web Server in front of your servlet container and install/configure the following modules:

• mod-deflate
• mod-expire
• mod-proxy-ajp (note that this depends on mod-proxy that you also need to install)

Modify your Apache configuration file to load the different modules:

and configure your different modules as described below:

Mod Deflate Configuration

Mod Expire Configuration

Mod Proxy AJP Configuration

where ajp://192.168.1.181:8009/xwiki is the internal address of your Servlet container where XWiki is running.

Memory

You need to configure your Servlet container so that XWiki has enough memory. You'll need to tune the value to your need. You should check the logs and see if there are any "out of memory" errors. Here are some good default values:

• Small installs: A minimum of 300MB of heap memory and 196MB of permGen (-Xmx300m -XX:MaxPermSize=196m)
• Medium installs: 512MB for the heap and 196MB of permGen (-Xmx512m -XX:MaxPermSize=196m)
• Large installs: 800MB for the heap and 196MB of permGen (-Xmx800m -XX:MaxPermSize=196m). Try not to ge beyond 1024MB since adding more memory means more GC time and thus lower performance.

For your information here are the values used for the xwiki.org site:

Database Indexes

Make sure you've set Database indexes. This is especially important when you start having lots of documents.

Panels

Some panels take more resources than others. For example the Navigation panel should NOT be used for wikis with a lot of documents since it displays all documents in the wiki. In the future that panel should be improved for performance but that's not the case right now. Originally this panel was only meant as a starting point. A better approach is to use a "Quick Links Panel" as we've now set up in the default XWiki Enterprise wiki version 1.1 (we've removed the default usage of the Navigation Panel in that version).

Robots.txt

If your wiki is open on the Internet, it'll be crawled by search robots (like GoogleBot, etc). They will call all the URLs and especially the ones that are resource hungry like exports (PDF/RTF). You need to protect against this. To do so configure a robots.txt file like this one and put it in your webserver configuration:

Note:

For Tomcat6 the placement of the robots.txt file should be within the $TOMCAT/webapps/ROOT folder and should have permission 644 applied.

In order to test if the robots.txt file is either accessable or working as desired use this checker.

Statistics

The statistics module is off by default since it's quite database intensive. If you don't need it you should turn it off.

Monitoring

More a developer-oriented feature, XWiki can monitor its own code, reporting the time spent for each sub-component activated during a request. While the monitoring code isn't time consuming, it increases the memory consumption a bit, and the create/start/stop/log/destroy calls are spread all around the code, so you will save a lot of method calls by disabling this. You can do that by setting the following line in xwiki.cfg:

Cache sizes

Tune the document cache in xwiki.cfg. The value depends on how much memory you have. The higher the better. A good reasonable value is 1000.

Cache Macro

It's possible to perform selective content caching by using the Cache Macro.

Rendering cache

Some pages are complex to render (they may aggregate outside data for example or do complex and slow queries). For theses pages you can use rendering cache.

Configuration based

Pages can be cached (i.e. their rendered content cached) to speed up displaying. The configuration is done in xwiki.properties with the following configuration options:

You can force a page to refresh using refresh=1 in the URL.

Enabled using velocity in document content itself (XWiki 1.0 syntax only)

You can add the following to their content to cache them after they are rendered. Note that the document is refreshed whenever the content of the document changes, and the cache takes into account the URL, so it is pretty safe to add a long cache duration for all documents that don't contain scripts gathering data from the wiki. For example to cache the rendered content for 60 seconds you would add:

Since 1.5M2, you can set the default rendering cache duration for all pages in xwiki.cfg:

Setting the default cache duration to a large value, and manually disabling the cache in dynamic pages would really speed up the wiki, since the rendering is one of the most time consuming processes.

Merge the CSS files

In order to reduce the number of requests and files that are downloaded from the browser or client, it could help to merge all XWiki CSS files into a single one. See the Merge CSS Script.

Set up NginX

If you experience heavy loads on your wiki, you could try using NginX.

NginX is used to fetch static content: images, javascript, styles, etc, but it can also be used as a reverse-proxy to pass requests down to the web container (e.g. Tomcat on port 8080).

Unlike Apache, which instantiates a new process per every static file, NginX uses the same process to fetch all the static data, and thus gives you extra perfomance "for free". 

For more info on setting up NginX check this guide.

Backlinks

While a pretty neat feature, keeping track of the backlinks has a medium impact on the document saving time and a minor impact on the document loading time. If you feel that your wiki does not need backlinks, you can safely disable them with the following line in xwiki.cfg:

Versioning

One of the key features of any wiki system, versioning greatly affects the database size and the document update time. If you are sure your wiki does not need to keep track of all the changes and you will never need to revert documents to a previous version, then you can add the following line in xwiki.cfg:

Custom Mapping

In some cases you may not want to rely on XWiki's generic database schema for storing XClass data and instead you'd like to provide your own optimized table. For these use cases you can use Custom Mapping.

Wiki syntax features for XWiki Syntax 1.0

If you don't plan to use all of the wiki features, like the strikethrough filter, the automatic http links filter, the SVG, Laszlo or style macros, you can disable them in xwiki-core-*.jar/META-INF/services/com.xpn.xwiki.render.*. The wiki rendering is the most costly operation in the rendering process, so any disabled feature counts.