[squid-users] squid stores multiple copies of identical ETags

[Tabacchiera, Stefano]

Alex,
first of all, thank you for your clarification.

>    Squid does not know that the response headers and body have not changed.
>    Squid could, in theory, trust the URL+Vary+ETag+etc. combination as a
>    precise response identity, but it is a bit risky to do that by default
>    because ETags/etc. might lie. There is currently no code implementing
>    that optimization either.

Ok, now I know that only URL/Vary are taken into account when storing an object.

>    To be more accurate, Squid does not store multiple copies of (what Squid
>    considers to be) the same response -- only one object can be indexed per
>    URL/Vary. Bugs notwithstanding, Squid will overwrite the old response
>    (for some definition of "overwrite") with the new one.

Since in my case there's no Vary header and the object Full URL never changes,
I',m starting to think about a bug (?!).

>    I do not know much about aufs -- that code has been neglected for a
>    while -- but perhaps aufs simply does not have enough time to delete its
>    old/unused files? Try setting cache_swap_low and cache_swap_high to the
>    same very low value, perhaps even zero (to avoid backgrounding the
>  cleanup task).

Uhm, are you saying that the the process of an object replacement on disk is not atomic?
I mean: squid would store a new copy of the object while leaving the old copy deletion to cleanup task?
If it's not, I still suspect a bug.
I'm hesitant to to turn the store_log on, 'cause the performance impact.
Btw, is there a specific debug_option?

Thanks a lot.
ST


____________________________________________________________________________________ La presente comunicazione ed i suoi allegati e' destinata esclusivamente ai destinatari. Qualsiasi suo utilizzo, comunicazione o diffusione non autorizzata e' proibita. Se ha ricevuto questa comunicazione per errore, la preghiamo di darne immediata comunicazione al mittente e di cancellare tutte le informazioni erroneamente acquisite. Grazie This message and its attachments are intended only for use by the addressees. Any use, re-transmission or dissemination not authorized of it is prohibited. If you received this e-mail in error, please inform the sender immediately and delete all the material. Thank you.