[Seaside] slow picture loading

Tue Nov 27 19:34:39 UTC 2012

Hi Bob and James,

Thanks again.

It seems to be that the 15s is too much of a coincidence :).

I put together two experiments that show that the loading problem depends on the amount of images:

- a page with 3 extra images on top of the template. This seems to exhibit the problem for exactly one slow loading image:
http://www.humane-assessment.com/test3ExtraImages

- a page with only 1 extra image on top of the template. This loads fine:
http://www.humane-assessment.com/testOneExtraImage

But, I still do not quite understand where to look next. Any further advice?

Cheers,
Doru

On 26 Nov 2012, at 20:41, Bob Arning <arning315 at comcast.net> wrote:

> I wrote a Squeak simulation of the browser loading 14 of the files on your page. I used a separate process for each httpGet: and typically were complete in under 1.5 seconds. When I hit reload on the browser, there are often 1 or 2 files taking a bit over 15 seconds. Suggests something different about how the browser requests data vs. my simple simulation.
> 
> Interesting that the response headers are:
> 
> HTTP/1.1 304 Not Modified
> Date: Mon, 26 Nov 2012 19:19:23 GMT
> Server: Apache/2.2.8 (Ubuntu)
> Connection: Keep-Alive
> Keep-Alive: timeout=15, max=100
> ETag: "392802a-7974-4cf387f145600"
> 
> Is it just a coincidence that the keep-alive timeout is 15 seconds and that the slow files take 15.7 seconds? Attached is an HAR file with the browser timing details.
> 
> Cheers,
> Bob
> 
> On 11/26/12 4:27 AM, Tudor Girba wrote:
>> Hi Paul, hi James,
>> 
>> Thanks for the answers.
>> 
>> I also thought it has to do with the Apache config, but I had no idea what to look for. Your suggestion certainly look interesting to look into, but I have close to no clue of how to do it. Do you happen to have a bit more hands-on pointers for         how to:
>> - increase the resources count
>> - add expire headers for the images
>> 
>> ?
>> 
>> Cheers,
>> Doru
>> 
>> 
>> On Mon, Nov 26, 2012 at 5:28 AM, Paul DeBruicker <pdebruic at gmail.com> wrote:
>> I suspect James has the answer but you might also consider doing the
>> following:
>> 
>> -Add expires headers for the images in Apache and people will only have
>> to download them once.
>> 
>> -Apache 2.2.8 was released Jan 19, 2008 so I'd definitely spend time
>> upgrading to the latest stable version just to get the security
>> vulnerability fixes.
>> 
>> 
>> 
>> On 11/25/2012 08:11 PM, James Foster wrote:
>> > Hi Doru,
>> >
>> > How many resources do you have loading from the same site? Once I had a problem in which Apache was configured (by default) to only provide ten (10) items per second to the same client. I believe this was an attempt to avoid a denial-of-service attack. When I changed Apache to allow 30 items per second then my site loaded much faster.
>> >
>> > James
>> >
>> > On Nov 25, 2012, at 3:24 PM, Tudor Girba wrote:
>> >
>> >> Thanks. But, somehow, I think size is not really the issue.
>> >>
>> >> Somehow randomly, one or two of the pictures take significantly more (the delta is measured in seconds) to load than the others.
>> >>
>> >> And yes, I am using the timeline debugging functionality from the browser.
>> >>
>> >> It's strange.
>> >>
>> >> Doru
>> >>
>> >> On 24 Nov 2012, at 10:26, Gerhard Obermann <obi068 at gmail.com> wrote:
>> >>
>> >>> Hi Doru,
>> >>>
>> >>> I would reduce the image size to the displayed size and reduce the bit depth of the png to 8.
>> >>> I tried it with home-icons-400-200-37.png.
>> >>> Before: 31.092 Bytes
>> >>> After: 7.678 Bytes
>> >>>
>> >>> Cheers
>> >>> Gerhard
>> >>>
>> >>>
>> >>> On Sat, Nov 24, 2012 at 8:29 AM, Tudor Girba <tudor at tudorgirba.com> wrote:
>> >>> Hi,
>> >>>
>> >>> I am working on a pier page, and I have a couple of images in it that seem to be slow to load, although they are served through apache.
>> >>>
>> >>> It is true that the images are slightly large (~230K), but still I think they appear too slow.
>> >>>
>> >>> The example is here:
>> >>> http://www.humane-assessment.com/
>> >>>
>> >>> Anyone has any idea of why this would happen?
>> >>>
>> >>> Cheers,
>> >>> Doru
>> >>>
>> >>>
>> >>> --
>> >>> www.tudorgirba.com
>> >>>
>> >>> "Live like you mean it."
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