Update: With the Max Idle set to 1, I'm still seeing regular cases of the 
scheduler starting a new instance when the previous instance is sitting idle, 
and a couple of seconds have passed since the last request was handled.

Should I file a production issue?  "Scheduler starts a new instance for no 
apparent reason" or something to that effect?

On Sep 6, 2011, at 9:53 AM, Joshua Smith wrote:

> I think I've found a case of either a schedule bug, or an example of 
> "expected" schedule behavior which is inscrutable.
> 
> At the end of last week, I adjusted my code so that it would avoid queuing 
> two tasks on top of each other, and that stabilized my instances at 1.  
> (Performance is set to Automatic idle instances, and 1.0s min pend latency.)  
> However, about 15 hours ago, my instances started bouncing up and down.
> 
> <PastedGraphic-5.png>
> 
> If we zoom in on the end:
> <PastedGraphic-6.png>
> 
> So let's look at that bump about two hours ago:
> 
> <PastedGraphic-7.png>
> 
> As you can see, the system created a new instance when I had one idle, 
> serving quickly, and with no other requests for over a minute.
> 
> Google overlords: Why would it create that instance?
> 
> (It would be really helpful if you put some info with that "this request 
> caused a new process" message, which helped us understand WHY!)
> 
> The only thing unusual about this request is that it came from a different 
> host than the previous request.  Is there a heuristic in the scheduler having 
> to do with the number of different inbound IP addresses?  (With a critical 
> change on the transition from 1 to 2?)
> 
> I'm going to now set Max Idle Instances down to 1 (down from Auto, which was 
> behaving the same as 1 until this morning).  And see if it eliminates the 
> sawtooth pattern…
> 
> -Joshua
> 
> 
> 
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