Optimizing Kallithea Performance

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

• Kallithea will perform better on machines with faster disks (SSD/SAN). It's more important to have a faster disk than a faster CPU.
• Slowness on initial page can be easily fixed by grouping repositories, and/or increasing cache size (see below). This includes using the 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 the main page. Having several hundreds of repositories on main page can sometimes make the system behave slowly when the cache expires for all of them. Increasing the expire option to a 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 the cache for repositories that have been changed.

2. Switch from sqlite to postgres or mysql

   sqlite is a good option when having a small load on the system. But due to locking issues with sqlite, it is not recommended to use it for larger deployments. Switching to mysql or postgres will result in an immediate performance increase. A tool like SQLAlchemyGrate can be used for migrating to another database platform.

3. Scale Kallithea horizontally

   Scaling horizontally can give huge performance increases 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 its own .ini file and unique instance_id set.
   • Each instance's 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 is used for task locking (so it is safe across multiple instances). Set the cache_dir, index_dir, beaker.cache.data_dir, beaker.cache.lock_dir variables in each .ini file to a shared location across Kallithea instances
   • If celery is used each instance should run a separate Celery instance, but the message broker should be common to all of them (e.g., one shared RabbitMQ 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.