Thanks Nick. I was so pee-ed off thinking about this earlier, wondering why I couldn't find more about it, and I held a tiny hope that maybe it was because it had been removed as an issue, more or less. So this is something of a relief!
I guess the next question is along the same lines of Ulrich's - what exactly disqualifies your app from auto scaling? What does 'many requests over one second' mean? Is 'many' more than an absolute number or more than or more than a certain percentage of requests or? Or is it based on an average latency? If one of the first two cases, could this mean your app might have problems if a certain portion of its requests were high latency, even if the rest were very low latency? Even if the average latency was less than 1s? I guess I'm just trying to figure out what number of proportion of requests I can afford to have high latency, for example for background worker requests etc. Cheers. On Apr 10, 4:18 pm, "Nick Johnson (Google)" <[email protected]> wrote: > Hi Peter, > > The simultaneous dynamic request limit was eliminated in a recent SDK. It > has been replaced with the flexible provisioning system detailed in the FAQ > entry you quote. > > It's correct that as long as you keep your latencies low, you should never > run into any sort of request limit. > > -Nick Johnson > > > > > > On Sat, Apr 10, 2010 at 2:12 PM, peterk <[email protected]> wrote: > > I've been using and watching appengine since, well, the beginning, and > > only by a random Google about an unrelated topic did I find out about > > this notion of a cap on 'simultaneous active requests'. I came across > > discussions where people were saying that there is a cap of 30 > > simultaneous active requests, citing the Quota page and so on. > > > But when I go to the Quota page - there's not a single mention of any > > such limit. Why not? Has something changed? > > > Reading the quotas on that page it's easy to conclude - naively > > perhaps in hindsight - that 500 requests/second is 500 requests/second > > irrespective of the average execution time of those requests. > > > There is no mention of any assumption on that page about the time > > taken to serve a request or anything else that goes into the > > calculation for 500 requests/second. > > > After some further searching I finally found mention of this limit in > > the FAQs, but here it's still quite vague - and again, no specific > > mention of this 30 simultaneous request limit. It says: > > > "However, App Engine reserves automatic scaling capacity for > > applications with low latency, where the application responds to > > requests in less than one second. Applications with very high latency > > (over one second per request for many requests) are limited by the > > system, and require a special exemption in order to have a large > > number of simultaneous dynamic requests. If your application has a > > strong need for a high throughput of long-running requests, you can > > request an exemption from the simultaneous dynamic request limit. The > > vast majority of applications do not require any exemption." > > > Which doesn't imply a hard limit, but rather that as long as your > > (average?) request fulfilment time is below one second you shouldn't > > have to worry about this. To be very exacting, if I keep my average > > request time under 1 second I should *never* see an error relating to > > this cap? This is a bit different than the talk of 30 simultaneous > > requests max - at that level with the max of 500 requests a second, > > you'd be limited to an average request time of 60ms! > > > So what is the story here? Why is this all being talked about in the > > shadows of message boards with no clear policy? Why isn't this > > limitation in the quota page? I thought I had GAE all figured out but > > then this ball gets thrown into the mix out of left field. > > > -- > > You received this message because you are subscribed to the Google Groups > > "Google App Engine" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]<google-appengine%2Bunsubscrib > > [email protected]> > > . > > For more options, visit this group at > >http://groups.google.com/group/google-appengine?hl=en. > > -- > Nick Johnson, Developer Programs Engineer, App Engine Google Ireland Ltd. :: > Registered in Dublin, Ireland, Registration Number: 368047 > Google Ireland Ltd. :: Registered in Dublin, Ireland, Registration Number: > 368047 -- You received this message because you are subscribed to the Google Groups "Google App Engine" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en.
