Custom ValueCache slower than custom CacheMap

[KammererTob]

Hi there,

We use Java Dataloaders in our Spring Boot project for GraphQL (still with the outdated/archived graphql-kickstart library).

In our current implementation we use a custom CacheMap to cache values (wrapped in a CompletableFuture) between requests. Since this always was kind of a hacky way of doing a cross-request caching (this was before ValueCache was a thing) we wanted to switch over to use the default CacheMap and instead provide a custom ValueCache, which is a EhCache backed cross-request cache.

After implementing this i noticed that our performance noticeable got worse (response time for large requests). It is even worse than completely disabling the cache (i.e. always returning a failed CompletableFuture in the get Method of the ValueCache), so that it always uses the BatchLoaders to load from the Database (locally in my tests).

I am not entirely sure what causes this, or if this is expected, or if i am doing something wrong. Happy to help investigate this however i can.

Attached are two Timelines of my Profiling (always 5 large requests, after initially warming up the server/cache by executing the same request a few times before):

1. With caching completely disabled. Multi-threaded database lookup (i assume)
   

2. Cross-Request ValueCache with caching enabled: