I've observed the same. 
We have a single jar and we disabled the jersey class scanning but the warmup 
still needs 30/35 seconds.

Two weeks ago the startup times were around 15/20 seconds, then, one day (I 
don't remember when) the performance dropped.  

-- 
Stefano Ciccarelli
Sent with Sparrow (http://www.sparrowmailapp.com/?sig)


On Thursday 15 March 2012 at 22:30, Jeff Schnitzer wrote:

> It's hard to be certain, but it *seems* like the biggest delay is
> reading files from whatever it is that passes for a network
> filesystem. I've timed several parts of my app and the only
> reasonable explanation I can come up with is that classloading is
> painfully and erratically slow. This hypothesis is consistent with
> one quirky observed behavior - putting all your classes in a single
> jar file (instead of WEB-INF/classes) has a measurable (beneficial)
> effect on application startup time.
> 
> Jeff
> 
> On Thu, Mar 15, 2012 at 4:09 PM, Emanuele Ziglioli
> <[email protected]> wrote:
> > Has anyone managed to profile cold starts (I don't know whether that's
> > even possible) to see where they take most of the time?
> > Does the length of cold starts on GAE servers correspond to how long
> > it takes on the development server?
> > 
> > I use GAE for Java so what I'll write below reflects that.
> > I know the libraries I use employ annotations and that's got to have
> > an impact. Jaxb (coupled with restlet) for example has got a terrible
> > cold start time.
> > My warmup request does exactly that, it triggers a jaxb warmup. But
> > lately it has been failing. Since that seems to affect mostly the
> > warmup request, users don't seem to be affected terribly (we have very
> > low traffic at this stage though).
> > 
> > I wonder whether the Google Engineers could implement something
> > similar to what Android does: there's a resident Dalvik VM and all new
> > processes fork from it.
> > Our prototype process could have the jvm, the web server and all the
> > rest that's common. Just a thought.
> > 
> > E
> > 
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