BOOL, can be read and
set, but not
When there is more than one simultaneous cache miss for an object, Fastly will normally put all but one of those requests in a queue. Thus, only one cache miss causes an origin fetch and the rest wait for that response, a process known as request collapsing.
req.hash_ignore_busy overrides this behavior and forces all requests to behave independently. Enabling this may cause a large increase in origin traffic when objects are not in cache.
req.hash_ignore_busy is used in the following code examples. Examples apply VCL to real-world use cases and can be deployed as they are, or adapted for your own service. See the full list of code examples 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.