Ayende @ Rahien

My name is Oren Eini
Founder of Hibernating Rhinos LTD and RavenDB.
You can reach me by phone or email:


+972 52-548-6969

, @ Q c

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Bug HuntWhat made this blog slow?

A while ago the blog start taking 100% CPU on the client machines. Obviously we were doing something very wrong there, but what exactly was it?

We track down the problem to the following code, can you figure out what the problem?



More posts in "Bug Hunt" series:

  1. (30 Jan 2012) What made this blog slow?
  2. (27 Jan 2012) What made this blog slow?



ajaxComplete calls fetchResults causes ajaxComplete causes fetchResults....

Josh Reuben

IIS applicationPool MaxConcurrentRequestsPerCPU ?


ajaxComplete triggers fetchResults which in turn triggers ajaxComplete

Ryan Heath

Each and every ajax call will trigger an ajaxComplete, which will trigger an ajax get, which will trigger an ajaxComplete, which will trigger an ajax get, which etc etc ... ;)

// Ryan

Frank Quednau

Kudos ayende for not misusing your position with regard of having the keenest and fastest bug finders.

PS I regularly must reload your captchas because they are hard. I am staring at what seems to be hebrew...

Matt Owen

I just happened to have Fiddler and this blog open on the day this happened. I saw the madness for myself. Hilarity ensued.

Rob White

ajaxComplete -> fetchResults -> ajaxComplete etc.

Even on a Friday, after a drink I spotted that one.

I assume that the real scenario was not as clearly presented.

More hard things please. ;-)

João Bragança

It would have worked if the profiler itself did not return X-RavenDb-Profiling-Id. Unless the profiler markup / js also needs this


I'm tempted to say stuff like "idiotic", "stupid" and "wtf?!". But I'm not going to.


I assume the fix is :-

if (!id) fetchresults(id.split(', '));

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