Understanding nukes & the expiration thread

[BUSTARRET, Jean-francois]

If I understand correctly how varnish works :
- the expiration thread (exp_timer) only checks the root of the binheap (= the oldest object currently in cache)
- a worker needing to free some space in the cache will nuke (EXP_NukeOne) the least recently used object (not taking into account lru_timeout)
 
which means :
- exp_timer can be "forever" checking a valid/very high ttl content
- EXP_Nuke can often nuke valid (medium traffic/high ttl) content, leaving expired (high traffic/low ttl) untouched
 
Am I right ?
I yes, shouldn't be better to have exp_timer look deeper ?
 
Jean-François Bustarret
WAT - Responsable technique
http://www.wat.tv
 
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