Posts tagged FAQ
A lot of the customer support queries we get at MemCachier are about client timeouts. It’s unusual for these to be due to problems with our infrastructure – we have a sensitive monitoring system that alerts us quickly when there are problems with the machines we use to host MemCachier caches. The timeouts that clients see are most often the result of transient network glitches and problems with client libraries. In this article, we’re going to try to explain a little of what’s going on.
Caching is a technique used in a wide range of contexts to increase the performance of storage systems. For example, modern microprocessors all have fast cache memory built into them, so that repeated accesses to the same memory addresses come from the fast cache storage, rather than from the slower main memory. In a similar way, operating systems maintain a cache of disk buffers in main memory, so that repeated reads from the same disk blocks come from the cached data rather than needing to be read from disk, which is much slower than memory.
The same kinds of considerations apply to caching for web and mobile applications with Memcache. In this case, it’s common to cache the results of database queries, partial page renders, or the results of other application-specific computations.
In any caching application, there are two questions that have to be answered. First, “What should I cache?” and second, “How big a cache do I need?”.
In many cases, the answer to the first question is determined by the web framework you use. For example, Django, Laravel, Spring Boot and others all have integrated caching systems that simplify the caching of database query results and HTML page renders. These frameworks usually also expose a lower-level API for doing application-specific custom caching.
However, the second question is trickier. At MemCachier, we get questions about cache sizing from customers all the time. Fortunately, there is a simple and systematic way to go about choosing a cache size, which we’re going to describe in this article.
