Redis new data structure: the HyperLogLog - Antirez weblog

A neat algorithm for counting large sets of items using a small data structure, using hashing and some intelligent statistics.

to algorithms cardinality counting hyperloglog scalability ... on 29 May 2014

The C10K problem

Web server scalability writeup from a few years. It's still interesting reading.

to concurrency networking programming research scalability web ... on 13 August 2006