Optimizing Kallithea Performance

When serving large amount of big repositories Kallithea can start performing slower than expected. Because of demanding nature of handling large amount of data from version control systems here are some tips how to get the best performance.

• Kallithea will perform better on machines with faster disks (SSD/SAN). It's more important to have faster disk than faster CPU.
• Slowness on initial page can be easily fixed by grouping repositories, and/or increasing cache size (see below), that includes using lightweight dashboard option and vcs_full_cache setting in .ini file

Follow these few steps to improve performance of Kallithea system.

1. Increase cache

   in the .ini file:

   beaker.cache.sql_cache_long.expire=3600 <-- set this to higher number
   

   This option affects the cache expiration time for main page. Having few hundreds of repositories on main page can sometimes make the system to behave slow when cache expires for all of them. Increasing expire option to day (86400) or a week (604800) will improve general response times for the main page. Kallithea has an intelligent cache expiration system and it will expire cache for repositories that had been changed.

2. Switch from sqlite to postgres or mysql

   sqlite is a good option when having small load on the system. But due to locking issues with sqlite, it's not recommended to use it for larger setup. Switching to mysql or postgres will result in a immediate performance increase.

3. Scale Kallithea horizontally

   Scaling horizontally can give huge performance increase when dealing with large traffic (large amount of users, CI servers etc). Kallithea can be scaled horizontally on one (recommended) or multiple machines. In order to scale horizontally you need to do the following:

   • each instance needs it's own .ini file and unique instance_id set in them
   • each instance data storage needs to be configured to be stored on a shared disk storage, preferably together with repositories. This data dir contains template caches, sessions, whoosh index and it's used for tasks locking (so it's safe across multiple instances). Set the cache_dir, index_dir, beaker.cache.data_dir, beaker.cache.lock_dir variables in each .ini file to shared location across Kallithea instances
   • if celery is used each instance should run separate celery instance, but the message broken should be common to all of them (ex one rabbitmq shared server)
   • load balance using round robin or ip hash, recommended is writing LB rules that will separate regular user traffic from automated processes like CI servers or build bots.