The polling interval is a configuration variable that can be set in }APQ Settings cube and should be set to a reasonable value. Setting the value too low can lead to various locking situations, setting the value too high will cause delay the main process execution as the signal to continue with main process execution comes at periodic intervals.
Since there are no tools to control child threads from the main thread, the parallel processing algorithm implements two different timeouts for child thread monitoring to prevent main process stalling in the polling loops and thus having zombie processes running on the TM1 server.
First timeout is used to monitor if all child threads have initiated correctly within a specified time period. Two types of exception can happen during this period:
The child thread will not initiate and will exit before it started processing data (for example due to a data source error).
The child thread has time related issues during its prolog initialization (for example due to infinite loop in the prolog code or a source view that calculates slowly).