Re: [squid-users] Some pages loading very slow in 3.1.10 Stable

Amos Jeffries wrote:
> On 24/01/11 23:09, Michael Hendrie wrote:
>>
>> On 24/01/2011, at 8:17 PM, Saiful Alam wrote:
>>
>>>
>>> OK I have kept your suggestion in my mind, but right now I'm not in
>>> a position to buy two HDD's. May be I can afford to buy 15 days
>>> later. For the time being, my prime problem is the loading of two
>>> major sites from where my users download mp3. Those are
>>>
>>> www.music.com.bd and www.djmaza.com
>>>
>>
>> Seems to load fine for me but that doesn't mean your slow = my fine.
>>
>> I had issues with some random sites being "slow" with 3.1.10 and
>> tracked it down to squid trying to get AAAA records for the problem
>> sites (or objects pulled from other sites). Not sure why this was
>> occurring as IPv6 is not enabled on the OS. I didn't investigate too
>> much and just recompiled with --disable-ipv6 as it wasn't needed.
>> Doing so resolved my slow sites issue.
>>
>
> Seems like you actually had IPv6 partially enabled in the OS, and maybe
> a break in DNS or MTU.
>
> When Squid 3.1.10 starts up it probes the OS network capabilities to see
> if IPv6 connections can be made. When they are possible it enables
> things like AAAA to use those connections. --disable-ipv6 merely sets
> the result of that test to always be false.
>
> With a reasonably fast DNS response time (under a half second) AAAA
> lookups will not be noticeable.

I am one of those who live in Brazil and most lookups are slow
since the international lines from Brazil to the USA are
not properly sized.

The log of the DNS server shows that the lookup for the A record is
always preceded by the lookup of the AAAA record.

What is the point of doing AAAA record lookups and trying to use the result
and then reverting to A record lookups and succeeding with the connect() ?
It is a lot of overhead for systems connected to slowish WANs and
systems with *many* connections.
The latter category might get a performance increase if Squid
automagically detects that there is no IPv6 router or uses
a new configuration option 'network_has_ipv6_router'.

I did not find options to configure bind/named to ignore AAAA lookups either
so I would love to see Squid have the new option.

> With working MTU there will be almost zero lag from opening and
> attempting IPv6 connections on an IPv4-only network.
>
>>
>>> Don't know the reason, but music.com.bd loads very slow. And in
>>> firebug i see that the problem persists while loading 3 ads from
>>> ads.clicksor.com and some facebook widgets. Can you please check
>
> There you have the problem by the looks of it.
>
> Ad servers are very bad for being slow. They usually do a lot of
> processing or slow operations in the background before replying. Due to
> their tracking desires they do not permit proxies to cache and speed up
> their results. Some are more noticeable than others.
>
> Facebook is designed in a similar way which also suffers from these
> heavy processing delay problems on the APIs. But they do seem to be
> emitting useful cache controls on the static bits to avoid that.
>
> You have a choice:
> put up with it
> or
> block those URL from being fetched.
>
>>> and try to load these two domains if you're running a Squid 3.1.X
>>> version and see if everything is alright from your end.
>>>
>
> Amos
Received on Mon Jan 24 2011 - 20:39:46 MST