On Friday, we successfully deployed a new memcache project as part of our overall work to create a more scalable service. After the deploy, we needed to move a lot of data with minimum impact on service quality. To do this, we put together some code that moves data only as it is requested.
This process kept a minimum on service disruption but did cause Twitter to have a complex conversation with two sets of caches over the weekend and into today. This resulted in some caching issues—namely, the /home timeline cache wasn’t being updated correctly for everyone.Read more…