Load Parameters
Summary: Numbers that describe the current load on a system.
Sources: chapter1
Last updated: 2026-04-15
Load parameters are used to succinctly describe the current load on a system, which is the first step in discussing growth and scalability. The best choice of parameters depends on the architecture of the system (source: chapter1).
Examples of Load Parameters
- Requests per second to a web server.
- Ratio of reads to writes in a database.
- Simultaneously active users in a chat room.
- Hit rate on a cache.
- Fan-out load: In transaction processing systems, this is the number of requests to other services that we need to make in order to serve one incoming request (source: chapter1).
Case Study: Twitter
Twitter’s scaling challenge is not primarily due to tweet volume (4.6k/sec), but due to fan-out: each user follows many people, and each user is followed by many people (source: chapter1).