ASP.NET Core MVC Interview Question #143

What is in-memory caching and when should it be used?

Dependency Injection, Services, Error Handling, Logging & Performance Senior Advanced

Quick Interview Answer

IMemoryCache stores data in the memory of the current application process. It is useful for relatively small, frequently reused data that can be recreated and does not need to be shared across multiple server instances.

Detailed Explanation

Because each application instance has its own memory cache, it is not automatically consistent across a server farm. Cache entries also disappear when the process restarts.

Code Example

public Product? GetCached(int id)
{
    return _cache.GetOrCreate(
        $"product:{id}",
        entry =>
        {
            entry.AbsoluteExpirationRelativeToNow =
                TimeSpan.FromMinutes(5);
            return LoadProduct(id);
        });
}