N1QL/FTS use grpc version 1.17.
There seems to be a leak within grpc's resetTransport as pointed out here -
which is addressed by https://github.com/grpc/grpc-go/pull/2985 for version 1.24
Consider upgrading grpc within these projects to v1.24.0?
The leak is coming from context.WithCancel as pointed out here: https://github.com/grpc/grpc-go/issues/2976.
Setting a timeout with context is a workaround for this - by setting a deadline for the datastore.IndexConnection which is handed to n1fty's Search(..). But WithTimeout for context was introduced in 7.0, so this is not a viable workaround for older builds.