varnish too fast for Captcha image with IIS backend

[Caunter, Stefan]

Greetings:

 

We have an email article pop-up with a captcha that works, when hit
directly on a relatively slow IIS7 backend, since it has "time" to
generate and get served as part of the pop-up. 

 

I observe that when we accelerate with varnish, the pop-up loads too
quickly, and the captcha image is not built in time, so varnish serves a
404 to the client, and the image is not there. Upon refresh it has been
built and gets served. I am using client director and pipe (necessarily)
to ensure we hit the same backend for the correct captcha and
corresponding transactions. 

 

Is an individual 404 something to which we can introduce a small delay,
or a restart? 

 

Can we potentially build a delay into vcl for the individual captcha
requests to compensate for this slowness since these are not cacheable?
Has anyone implemented a "patience" subroutine?

 

Stefan Caunter :: Senior Systems Administrator :: TOPS

e: scaunter at topscms.com  ::  m: (416) 561-4871

www.thestar.com www.topscms.com

 

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