Krzysztof Olędzki wrote:
On 2010-03-20 02:29, Amos Jeffries wrote:
Krzysztof Olędzki wrote:
Hello,
Hello,
I'm have been trying to configure Squid to store and provide two
versions of the same obiect, but so far with no luck.
I configured my load balancer to append an additional header to
a request depending on a client status, something like:
"X-ASP-CFlag: Yes" or "X-ASP-CFlag: No"
I also configured my servers to append "Vary: X-ASP-CFlag" and to
set a different ETag for both responses.
Squid is able to cache such responses and always provide a correct
version, so I believe I did everyting correct releated to handling
Vary& ETag.
My problem is that each time, when a different type of client comes,
the object is RELEASED and Squid fetches a new one. So, Squid
is able to provide a cached version of such obiect as long as
consecutive requests come from the same type of a client. If they comes
from the different type, then I get 0% hit rate. :(
Is Vary always set regardless of X-ASP-CFlag presence?
Yes, Vary should be always set and the same goes for X-ASP-CFlag.
missing X-ASP-CFlag is considered to be one of the three variant cases
by Squid (missing, "Yes", "No").
It is not possible for X-ASP-CFlag to be empty.
Is the ETag the same for both variants?
No.
What does Cache-Control: header contain for each/both?
Don't know. I'll check this. Does it make any different if they are
distinct?
Not really if they are different. What matters is the content, what CC
is instructing Squid to do.
This goes for Cache-Control: header in both the request AND reply.
If either contains no-store, private, no-cache, must-revalidate, or a
maxage < the stored object age Squid is forced to re-fetch and replace
the relevant objects.
1269025015.033 23 192.168.162.1/192.168.152.2 TCP_MISS/200
16857 GET http://www.example.com/xml/EF.001.xml -
FIRST_UP_PARENT/192.168.162.1 text/xml
1269025022.400 27 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16886 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025022.863 81 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16886 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025022.967 25 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16886 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025023.456 1 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16886 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025024.015 21 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16886 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025024.101 16 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16887 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025025.836 1 192.168.162.1/192.168.152.2 TCP_MEM_HIT/200
16887 GET http://www.example.com/xml/EF.001.xml - NONE/- text/xml
1269025028.506 27 192.168.162.1/192.168.152.2 TCP_MISS/200
100934 GET http://www.example.com/xml/EF.001.xml -
FIRST_UP_PARENT/192.168.162.1 text/xml
... client B first request.
1269025031.030 37 192.168.162.1/192.168.152.2 TCP_MISS/200
16904 GET http://www.example.com/xml/EF.001.xml -
FIRST_UP_PARENT/192.168.162.1 text/xml
1269025033.208 11 192.168.162.1/192.168.152.2 TCP_MISS/200
100934 GET http://www.example.com/xml/EF.001.xml -
FIRST_UP_PARENT/192.168.162.1 text/xml
... client B second request.
Notice how the object size keeps changing with each TCP_MISS. Might be
related.
The size is different because the object is different. :)
According to the store.log I have:
- request from a client type "A":
1269025015.023 RELEASE 00 00032DDE 3670265D41E40D46FB58467B0A406016
200 1269025002 1268659805 1269025062 text/css -1/16369 GET
http://www.example.com/css/EF.001.css
1269025015.023 SWAPOUT 00 000332CA 26DF93F5ACF8EFF960D1ABD01F1D9509
200 1269025015 -1 1269125015 x-squid-internal/vary -1/220 GET
http://www.example.com/css/EF.001.css
1269025015.023 RELEASE 00 00032F03 BA73564A12C40FB51174FE3CD14F2BDA
200 1269025005 -1 1269125005 x-squid-internal/vary -1/220 GET
http://www.example.com/css/EF.001.css
1269025015.033 SWAPOUT 00 000332CC E3A743051428428E9D4D45836CB2719C
200 1269025014 1268659805 1269025074 text/css -1/16338 GET
http://www.example.com/css/EF.001.css
- request from a client type "B":
1269025028.491 RELEASE 00 00032F04 F7F9BF630687B86AFAA4D5CD729E6F15
200 1269025005 1268659805 -1 text/xml 100483/100483 GET
http://www.example.com/xml/EF.001.xml
1269025028.491 SWAPOUT 00 00033BEA 26DF93F5ACF8EFF960D1ABD01F1D9509
200 1269025028 -1 1269125028 x-squid-internal/vary -1/220 GET
http://www.example.com/xml/EF.001.xml
1269025028.491 RELEASE 00 000332CA 80E0AD812ADE72183FD2BF19D3D1F251
200 1269025015 -1 1269125015 x-squid-internal/vary -1/-218 GET
http://www.example.com/xml/EF.001.xml
1269025028.506 SWAPOUT 00 00033BF0 A070DC36FD8ED3452573EE7DC398DF53
200 1269025028 1268659805 1269025088 text/xml 100483/100483 GET
http://www.example.com/xml/EF.001.xml
- request from a client type "A":
1269025031.015 RELEASE 00 000332CC BCB90FADA1A3A323B25925C4776B64AB
200 1269025014 1268659805 1269025074 text/xml -1/16338 GET
http://www.example.com/xml/EF.001.xml
1269025031.015 SWAPOUT 00 00033D2D 26DF93F5ACF8EFF960D1ABD01F1D9509
200 1269025031 -1 1269125031 x-squid-internal/vary -1/220 GET
http://www.example.com/xml/EF.001.xml
1269025031.015 RELEASE 00 00033BEA C4D3004363864A9BC877E75165903539
200 1269025028 -1 1269125028 x-squid-internal/vary -1/220 GET
http://www.example.com/xml/EF.001.xml
1269025031.028 SWAPOUT 00 00033D2A E3A743051428428E9D4D45836CB2719C
200 1269025030 1268659805 1269025090 text/xml -1/16385 GET
http://www.example.com/xml/EF.001.xml
- request from a client type "B":
1269025033.204 RELEASE 00 00033BF0 4A2CE9062319A7E381086826978BCBB3
200 1269025028 1268659805 1269025088 text/xml 100483/100483 GET
http://www.example.com/xml/EF.001.xml
1269025033.204 SWAPOUT 00 00033EE7 26DF93F5ACF8EFF960D1ABD01F1D9509
200 1269025033 -1 1269125033 x-squid-internal/vary -1/220 GET
http://www.example.com/xml/EF.001.xml
1269025033.204 RELEASE 00 00033D2D C5D2959AD4FB3A19CB4333A21A85A3F9
200 1269025031 -1 1269125031 x-squid-internal/vary -1/-218 GET
http://www.example.com/xml/EF.001.xml
1269025033.208 SWAPOUT 00 00033EE8 A070DC36FD8ED3452573EE7DC398DF53
200 1269025032 1268659805 1269025092 text/xml 100483/100483 GET
http://www.example.com/xml/EF.001.xml
And so on...
So, the question is: how to teach squid to do it in the right way?
Client A and B are requesting different objects one is a CSS one an XML
file.
There is no sign in access.log of those client A requests.
My bad, please s/css/xml/g. I made a mistake in masking real addresses
in the above example, but each time it was exactly the same url.
In that case ... that trace is clearly showing that A is storing its own
object and B is storing another, the request for A in the middle
replaces the original A object leaving the B one present. Then the
followup B replaces the original B object leaving the A one present.
Vary storing itself seems to be working, but something else is causing
the variants to be replace on each of their requests. This smells more
like a Cache-Control problem.
Amos
--
Please be using
Current Stable Squid 2.7.STABLE8 or 3.0.STABLE25
Current Beta Squid 3.1.0.18
