There's been a lot of discussion of the scheduler behavior in Pythonland,
but not much about it's "eccentricities" in Javaland.
I have a threadsafe=true Java app. Let's say every request completes in
exactly 1s. Settings are: idle instances min 1 max 1, latency auto/auto.
Here is what I expect:
* Instance1 starts up and becomes permanently resident
* Instance1 serves concurrent requests up to some arbitrary CPU capcity
* When Instance1 exceeds capacity:
* Instance2 starts warming up
* All requests remain in the pending queue for Instance1, getting
processed at 1/s * concurrency
* Instance2 is ready and starts processing new requests, sharing the
load with Instance1
What I actually see (as far as I can determine):
* Instance1 starts up and becomes permanently resident
* Instance1 supports almost no concurrency. At most it's 2. (no, my app
is not particularly compute intensive)
* A new request comes in which for some reason can't be handled by
Instance1:
* Instance2 starts warming up
* The new request is blocked on Instance2's pending queue, waiting
10-20s for Instance2 to be ready
* In the mean time, Instance1 is actually idle
* Another new request comes in and starts up Instance3
* Possibly this is while Instance2 is warming up
* AFAICT, Instance1 is taking a coffee break
The net result is that I have an idle website with 1 user (me) clicking
around and I've already gotten multiple 20s pauses and three instances.
Something is seriously wrong here. Whether or not it's rational to have
so many instances started, pending requests shouldn't be shunted to
non-warmed-up servers, right?
I've tried upping the min latency to a high value to see if this improves
the situation. If this works... shouldn't min latency *always* be as high
as the startup time for an instance?
I know it's been said before, but it needs to be said again... the guidance
for scheduler configuration is really, really inadequate.
Jeff
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