Re: Server response time discrepancy.

On Thu, Jun 19, 2008 at 03:06:42AM -0600, Unai Rodriguez wrote:
> Dear All,
>
> We are maintaining a site. All the server infrastructure is physically
> located in Singapore (including the HAProxy load balancer).
>
> We have experienced situations where people from USA had errors accessing
> the site but here from Singapore the site worked fine.
>
> We have been diving into HAProxy logs for a few days and discovered that
> the "Tr" values (aka server response time) when the site is being accessed
> from Singapore are about 10ms (or less) but when accessed from US is more
> than 40000ms. The difference is huge.
>
> A few log lines that illustrate this (please pay attention into the FOURTH
> digit):
>
> 1) Accesses from Singapore (Timing Events).-
> 4/0/2/9/311 (Tr = 9)
> 4/0/2/9/165 (Tr = 9)
> 12/0/2/2/20338 (Tr = 2)
> 8/0/1/2/364829 (Tr = 2)
> 8/0/2/2/390360 (Tr = 2)
> ---
>
> 2) Accesses from USA (Timing Events).-
> 3/0/2/43286/43409 (Tr = 43286)
> 3/0/3/56757/56883 (Tr = 56757)
> 4/0/1/40364/40580 (Tr = 40364)
> 3/0/4/102493/102616 (Tr = 102493)
> 4/0/3/125353/125487 (Tr = 125353)
> ---
>
> Do you think that there is something wrong with the network or the
> application? Are this values common (i.e. too high, too low...)?

These times are huge (and unacceptable). What I don't understand is why changing the location of the *client* has any impact on the *server* response time.

Ah, maybe I have an idea. Are those requests posts with large data ? In that case, the time for the client to post all data to the server will be included in the response time. If this is the case, you may like to log the request's Content-length header using :

  capture request header content-length

If this is not the problem, then I have no idea right now. BTW, the total time seems huge too (several minutes). Are you sure that "option httpclose" is set ? It should not impact server's response time, but it would be good to ensure that timers are correct.

Regards,
Willy Received on 2008/06/20 07:04