Client::_desc is initialized as the string "conn" rather than the string "conn" + session->id().
- https://github.com/mongodb/mongo/blob/r3.6.0/src/mongo/transport/service_state_machine.cpp#L231
- https://github.com/mongodb/mongo/blob/r3.6.0/src/mongo/db/service_context.cpp#L147
- https://github.com/mongodb/mongo/blob/r3.6.0/src/mongo/db/client.cpp#L112
Note: It is still possible to reconstruct the thread name via the "connectionId" field in the currentOp output.