Confluence Docs 3.0 : Performance Tuning This page last changed on Sep 21, 2009 by jlargman.
| This document describes tuning your application for improved performance. It is not a guide for troubleshooting Confluence outages. Check Troubleshooting Confluence Hanging or Crashing for help if Confluence is crashing. NEW: Garbage Collector Performance Issues
## Description Like any server application, Confluence may require some tuning as it is put under heavier use. We do our best to make sure Confluence performs well under a wide variety of circumstances, but there's no single configuration that is best for everyone's environment and usage patterns. If you are having problems with the performance of Confluence and need our help resolving them, you should read Requesting Performance Support. ## Use the latest version of your tools Use the latest versions of your application servers and Java runtime environments. Newer versions are usually better optimized for performance. As an example, our internal performance tests show a 20% speed-up (when viewing pages under load) between Tomcat 6 on Java 6 vs Tomcat 5.5 on Java 5 out of the box. ## Avoid swapping due to not enough RAM Always watch the swapping activity of your server. If there is not enough RAM available, your server may start swapping out some of Confluence's heap data to your hard disk. This will slow down the JVM's garbage collection considerably and affect Confluence's performance. In clustered installations, swapping can lead to a Cluster Panic due to Performance Problems. This is because swapping causes the JVM to pause during Garbage Collection, which in turn can break the inter-node communication required to keep the clustered nodes in sync. ## Choice of Database The embedded database that is provided with Confluence is meant only to be used for evaluation, not for production Confluence sites. After the evaluation finishes, you will certainly need to switch to an external relational database management system. Beyond this, we do not recommend any particular RDBMS over another. We recommend using what you are familiar with, because your ability to maintain the database will probably make far more difference to what you get out of it than the choice of database itself. ## Database Connection Pool If load on Confluence is high, you may need more simultaneous connections to the database. If you are using JNDI data-sources, you will do this in your application server's configuration files. If you have configured Confluence to access the database directly, you will need to manually edit the hibernate.c3p0.max_size property in the confluence.cfg.xml file in your confluence.home directory. After you have changed the URL in this file, restart Confluence. To assess whether you need to tune your database connection pool, take thread dumps during different times (including peak usage). Inspect how many threads have concurrent database connections. ## Database Indexes If Confluence is running slowly, one of the most likely cause is that there is some kind of bottleneck in the database. Especially if you have more than a few thousand active users, you should consider enaging a database administrator (DBA) to tune the database specifically to the demands that your particular Confluence installation is placing on it. If you do not have a full-time DBA and can't even get one for temporary consulting, you may want to consult the database indexing advice that we have been gathering from customer reports and our own experience running and developing Confluence. The instructions on that page are for Oracle, but most of the indexes can be applied to (and will help with) any database. (These database indexes are now created automatically when Confluence is installed, but existing installations upgrading to a more recent version may still need to add them manually) ## Cache Tuning To reduce the load on the database, and speed up many operations, Confluence keeps its own cache of data. Tuning the size of this cache may speed up Confluence (if the caches are too small), or reduce memory (if the caches are too big). Future versions of Confluence will allow you to tune the size of this cache from within the web application. Vote for tuning the cache from the UI and getting cache recommendations to encourage Atlassian to build this feature into a Confluence release. Please have a look at our documentation on Cache Performance Tuning for information on how to tune Confluence caches. ## Antivirus Software Antivirus software greatly decreases the performance of Confluence. Antivirus software that intercepts access to the hard disk is particularly detrimental, and may even cause errors with Confluence. You should configure your antivirus software to ignore the Confluence home directory, its index directory and any database-related directories. ## Enabling HTTP Compression If bandwidth is responsible for bottlenecking in your Confluence installation, you should consider enabling HTTP compression. This may also be useful when running an external facing instance to reduce your bandwidth costs. Take note of the known issues with HTTP compression in versions of Confluence prior to 2.8, which may result in high memory consumption. ## Virtual Operating Systems Virtual Environments such as VMWare can cause Confluence CPU to spike. Run Confluence on a native OS. See our List Of Supported Operating Systems. ## Performance Testing You should try out all configuration changes on a demo system. Ideally, you should run and customize loadtests that simulate user behaviour. Learn about how to test performance issues using the Performance Testing Scripts. ## Access logs You can find out which pages are slow and which users are accessing them by enabling Confluence's built-in access logging. ## Built-in Profiler You can identify the cause of page delays using Confluence's built-in profiler according to Troubleshooting Slow Performance Using Page Request Profiling. ## Adjust Application Server Memory Settings See Managing Application Server Memory Settings. ## Use A Web Server For high-load environments, performance can be improved by using a web server such as Apache in front of the application server. There is a configuration guide to Running Confluence behind Apache. When configuring your new web server, make sure you configure sufficient threads/processes to handle the load. This applies to both the web server and the application server connector, which are typically configured separately. If possible, you should enable connection pooling in your web server connections to the application server. ## Parallel GC If you have multiple CPU's on your server, you can add -XX:+UseParallelOldGC to your JAVA_OPTS options. This will allow garbage collection of the Tenured Space to happen in parallel with the application and can boost performance and can reduce slow performance spikes. For more information, please refer to our detailed page on Garbage Collector Performance Issues, and Sun's summary of collectors. ## Troubleshoot possible memory leaks Some external plugins, usually ones that have been written a long time ago and that are not actively maintained anymore, have been reported to consume memory and never return it. Ultimately this can lead to a crash, but first this manifests as reduced performance. The Troubleshooting Confluence Hanging or Crashing guide is a good place to start. Some of the known causes listed there could result in performance issues short of a crash or hang. ## Some 3rd-party plugins were not written to scale to large enterprises' needs Confluence has been optimized to work under high load and with many pages. Some 3rd party plugins however have been written with small size companies in mind, and can't cope with large numbers of concurrent users, or large numbers of pages and permissions, or large numbers of spaces. It is impossible to tell which ones will fail under which conditions, but it will always help to turn off 3rd-party plugins that are not strictly mission-critical while investigating performance issues. ##### RELATED TOPICS Garbage Collector Performance Issues Cache Performance Tuning Cache Performance Tuning for Specific Problems Performance Testing Scripts Working with Confluence Logs Operating Large or Mission-Critical Confluence Installations Confluence Clustering Overview Requesting Performance Support Administrators Guide Configuration Guide Attachments: confluence-coherence-cache-config-clustered.xml (text/xml) confluence-coherence-cache-config.xml (text/xml)

Document generated by Confluence on Nov 05, 2009 23:27