A WebClient is created for each call to makeOkapiRequest. This results in leak of sockets. They are closed probably at time of garbage collection which is not good enough. The problem has been seen in many other modules.

https://github.com/folio-org/mod-courses/blob/4401902d0d25334482afab2a8a46b48b91afd584/src/main/java/org/folio/coursereserves/util/CRUtil.java#L381

There is no webClient.close . This would prevent a leak, but make the HTTP communication much slower than it has to be.

Much better to use one WebClient per Vert.x instance (we have one) and the HTTP communication will use sockets from a shared pool.