title: Get total number of running greenlets in Gevent?
body: <p>Is there a way to query number of greenlets in current Gevent process, and the state of them?</p>
  
  <p>For example, I wanna crawle arbitary websites with arbitary greenlets, then I run another greenlet for query how many are running are how many are finished/exception.</p>
  
  <p>Or should I just set a global variable as counter? Does Gevent has something like that built-in?</p>