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p50 and p99

Percentiles of latency: half the requests are faster than the p50, 99% faster than the p99.

Taught in Chapter 1: The Request Path.

More from the same chapter

• App server: Runs the application's code: checks each request, talks to storage and builds the response.
• Client: Whatever the user holds, an app or a browser, that sends requests and waits for responses.
• Latency: How long one request takes, end to end.
• Read and write: A read fetches data without changing it; a write changes it. Most systems see 10 to 100 reads per write.
• Stateless: A server that keeps nothing between requests, so any copy of it can serve any request.
• Throughput: How many requests complete per second.