Each Sous-processus Arbortext PE has a flag which is set any time it returns a fatal error. When a work thread detects an unusable Sous-processus Arbortext PE, it sets a flag that records the state of the Sous-processus Arbortext PE. At a later time, the work thread scans all running Sous-processus Arbortext PE and requests the operating system to terminate any with the hung or fatal flag set to true.