In the case that a worker cannot be started (for example, connection limit of a database reached), the entire pool will crash. This is tragical with overflow workers, when requesting an overflow worker will crash the pool and all the linked existing workers.

In my case, I'm working in a tight environment where other things running on the same machine may simply exhaust the local ports. A new connection to the database is then not possible, which is somewhat ok, can always try later. However, I wouldn't know that unless starting an overflow worker is attempted, and then all the existing connections in the pool will crash.