In an optical connector for use in connecting an optical fiber, a shell member has an engaging portion. A transistor structure having a substrate, a gate, and a gate oxide layer between the substrate and the gate is formed. When suspension of the power supply from the backup power source reoccurs before completion of the reference value learning by the reference value learning section, a control section invalidates the determination of the remaining data determining section and performs the reference value learning, after the power supply is restored. A user is provided with an interface to select filtering rules for the threads, resulting in a set of filtered threads which are candidates for being in infinite wait conditions.