Facebook Pushes Limits for Memcached

When engineers discuss massive web scalability, the conversation often turns to memcached, the object caching system used to speed database-driven dynamic web application. Facebook has been among the sites that has leveraged the capabilities of memcached to keep pace with rapid audience growth.

“Here at Facebook, we’re likely the world’s largest user of memcached,” writes Paul Saab of the Facebook engineering team in a post that details how Facebook has refined its use of memcached to handle up to 200,000 UDP requests per second in production. “The total throughput achieved is 300,000 UDP requests/s, but the latency at that request rate is too high to be useful in our system,” Saab writes. “This is an amazing increase from 50,000 UDP requests/s using the stock version of Linux and memcached.”

See the Facebook Engineering Blog for details on how they’ve done it, and High Scalability for additional analysis.

Facebook said it hopes to get its enhancements incluced in the official memcached code, but in the meantime has published its changes to memcached on the social code repository github.