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From Leif H: "The proxy.config.http.cache.heuristic_max_lifetime is mostly correct, except for two things: 1) It does not get “flushed”, it merely says how long (max) it can cache objects under the heuristics rules. 2) It’s not a fixed setting, what it does is together with the “min” setting is to get a range for the Expire time, the effective TTL will be a value between min-max, based on how old the object is (based on Last-Modified). Since you set lm_factor=1.0, you did effectively set min == max == 3 months. This seems very aggressive, and counteracts how the heuristics system is supposed to work. The idea is that objects which are changing frequently you should cache much shorter than those which change infrequently."

True, I've since updated these settings may not be for everyone.

CONFIG proxy.config.http.cache.heuristic_maxmin_lifetime INT 7776000

There's an algorithm here that I don't fully understand, but this setting should guarantee that the relevant
information regarding an object's "last modified" date is fully support by the cache.

2592000
CONFIG proxy.config.http.cache.heuristic_max_lifetime INT 7776000
CONFIG proxy.config.http.cache.heuristic_lm_factor FLOAT 10.000000500000

Fuzzy Object Expiration Logic

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