Another common cache problem is the lag that can come when new or recently reset servers have to be repopulated with data in demand. When the local memory pool for a given client is empty and an application can't quickly get the data it needs, mcrouter can look in a neighboring "warm" pool that's already up-to-date with the bits that are in demand. After coming through in a pinch, mcrouter can then automatically start populating the new pool with data from the warm one.
This type of "reheating" problem has been a big one for Reddit, which is now testing mcrouter, said Ricky Ramirez, an operations engineer at the social media site. Reddit runs entirely on AWS and consumes up to 300 servers at a time, backed by 73 back-end cache nodes with 1TB of memory, he said in a presentation at the conference.
When memory pools have to be taken down for modification, reheating the cache can take days, during which some users get slow page loads and "random error messages," Ramirez said. Mcrouter gives Reddit automatic failover, pooling of connections and other benefits, he said.
Sign up for MIS Asia eNewsletters.