An application using the
Performance Metrics Application Programming Interface (PMAPI)
may manipulate several concurrent contexts,
each associated with a source of performance metrics, e.g. pmcd(1)
on some host, or an archive log of performance metrics as created by
pmlogger(1).
pmWhichContext
returns a handle for the current PMAPI context, that may
be used in the associated PMAPI routines that require a handle
to identify a PMAPI context.