A thread filter determines whether a detected event should be further considered for breakpoint processing.
thread_filter
The thread_id expressions are evaluated at the time the breakpoint command is entered, and each must yield an integer value.
A detected event is retained for further consideration only if the thread in which the event occurs matches one of the given threads. If not, the detection is quietly ignored.
If the thread_filter does not indicate a match, then any related logical filter is not evaluated.