Method and apparatus to enable collection of information required for solving a problem caused by simultaneous access to a shared resource in a multithreading environment. In an information processor capable of executing a routine including a tracing process of collecting information related to the processing status in multithreading, a routine being executed is registered for each thread being activated, and the level of the tracing process for the routine being executed is determined based on information in the registration. The tracing process level for the routine being executed can be determined based on whether any routine identical to, or in a predetermined relation with, the routine is already registered.