On Linux, every Client is associated with an eventfd file-handle, allowing the Baton to implement the Notifyable interface. The eventfd file handle is created lazily and during the first attempt to poll on the sockets associated with a Client. As a result, failing to create the eventfd handle (due to resource exhaustion) is no longer connection-fatal. We should either:

• Revert SERVER-87036 and make eventfd file handles upon creating new Client objects – we can limit the performance implications by doing so when a Session is supplied to the client, and otherwise keeping the existing behavior.
• Change the exception handling behavior to make this connection-fatal.