req.hash_ignore_busy
BOOL, can be read and set, but not unset.
Available inrecv
When there is more than one simultaneous cache miss for an object, Varnish will
normally put all but one of the threads handling those requests to sleep. Thus,
only one cache miss hits the origin and the rest wait for that response.
req.hash_ignore_busy overrides this behavior and lets all requests through
simultaneously.
Try it out
req.hash_ignore_busy is used in the following solution recipes. Recipes apply VCL to real-world use cases and can be deployed as-is, or adapted for your own service. See the full list of recipes for more inspiration.
Click RUN on a sample below to provision a Fastly service, execute the code on Fastly, and see how the function behaves.
Cache '429' rate-limiter responses per IP
If a backend returns a 429, cache it for the requesting IP but continue to allow other clients to use origin.