REST API (Jersey), grabs a context, and never frees/returns/releases it. I don't know exactly what is going on, but it causes the REST API to not be able to reflect real-time updates to content.
To repeat. Load a DSpace-REST result for some endpoint. Edit the title/name of the first object returned in that result. Reload the REST endpoint. For me, the REST response didn't have the updated title/name.
Since the typical use-case of DSpace is content that rarely/never changes, this isn't a big deal, but it needs to be resolved.
I believe this bug got in during the performance stress-testing process, where after hitting DSpace REST with millions of requests to Communities, Collections, Items, Bitstream over the span of an hour, I had added changes to help REST spend less time dealing with database connections, and instead keep a connection.
The better route would be to grab a database connection from the pool, and return the connection back to the pool once the request is complete. I think I/we need to take a look at database connection pool best practices.