max_connections, backend_busy, and queueing requests

[Per Buer]

Hi Jeff.

On Tue, May 22, 2012 at 5:05 PM, Jeff Potter
<jpotter-varnish at codepuppy.com>wrote:

>
> As soon as there are 500 concurrent requests, varnish kicks any additional
> requests to vcl_error and we send out a 5xx error for the requests. And
> varnishstats increments the backend_busy/"Backend conn. too many" counter.
>
> How do I get Varnish to queue up the requests instead, so that when a
> backend worker connection becomes available it gets sent to a backend?


Varnish, in it's current state doesn't do this, I'm afraid. Since Varnish
uses one thread, and thus has some overhead, for each connection it
wouldn't be ideal to have them idly wait. The current trunk code uses
separate threads to fetch content from the backend so having some sort of
queue there shouldn't be to hard. I don't know of any plans to implement
this, however.


-- 
Per Buer
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