Oracle wait event: pmon timer

select
   ses.program,
   ses.event,                           -- Likely: pmon timer
   ses.p1text,                          -- Likely: duration,
   ses.p1,                              -- Likely: 300  (i. e. 3 seconds)
   ses.wait_time_micro / 1e6 in_wait_s, -- < 3
   ses.state,
   ses.status
from
   v$session ses
where
   ses.type  = 'BACKGROUND' and
  (ses.program like '%(PMON)' or ses.program like '%(CL__)')
;