code: def collect(self):
          
          if not psutil:
              self.log.error('Unable to import psutil')
              self.log.error('No process resource metrics retrieved')
              return None
  
          for process in psutil.process_iter():
              self.collect_process_info(process)
  
          # publish results
          for pg_name, counters in self.processes_info.iteritems():
              if counters:
                  metrics = (
                      ("%s.%s" % (pg_name, key), value)
                      for key, value in counters.iteritems())
              else:
                  if self.processes[pg_name]['count_workers']:
                      metrics = (('%s.workers_count' % pg_name, 0), )
                  else:
                      metrics = ()
  
              [self.publish(*metric) for metric in metrics]
              # reinitialize process info
              self.processes_info[pg_name] = {}
docs: Collects resources usage of each process defined under the
          `process` subsection of the config file