What are the options to use JDBC in a non-blocking way in Play?

Question

I wonder what is the best (recommended, approved etc.) way to do non-blocking JDBC queries in Play! application using Play's connection pool (in Scala and to PostgreSQL if it matters)? I understand that JDBC is definitely blocking per se, but surely there are approaches to do the calls in separated threads (e.g. using futures or actors) to avoid blocking of the calling thread.

Suppose I decided to wrap the calls in futures, which execution context should I use, the Play's default one? Or it's better to create separated execution context for handling DB queries?

I know that there are some libraries for this like postgresql-async, but I really want to understand the mechanics :)

Answer 1

Suppose I decided to wrap the calls in futures, which execution context should I use, the Play's default one? Or it's better to create separated execution context for handling DB queries?

It is better to use separate execution context in this case. This way there will be no chance that your non-blocking jobs (most of the default Play's stuff) submitted to default execution context will be jammed by blocking JDBC calls in jobs you submit to the same execution context.

I suggest to read this (especially second part) to get a general idea of how you could deal with execution contexts in different situations (including case with blocking database queries), and then refer this to get more details on configuring your scenario in Play.