[Seaside] slow picture loading
Tudor Girba
tudor at tudorgirba.com
Tue Nov 27 21:00:06 UTC 2012
Hi Bob,
I changed the KeepAliveTimeout to 1. The situation improved significantly in that the delay is now just 1 sec :).
I will look into changing the ordering.
Cheers,
Doru
On 27 Nov 2012, at 21:29, Bob Arning <arning315 at comcast.net> wrote:
> Doru,
>
> Here are some suggestions:
>
> 1. Is it a browser issue? I'm seeing it in Chrome - MacOS 10.7.
> 2. See if tinkering with apache's keep-alive makes a difference. In /etc/apache2/httpd.conf (on a mac, anyway), there is this:
>
> # KeepAlive: Whether or not to allow persistent connections (more than
> # one request per connection). Set to "Off" to deactivate.
> #
> KeepAlive On
>
> # KeepAliveTimeout: Number of seconds to wait for the next request from the
> # same client on the same connection.
> #
> KeepAliveTimeout 15
>
> so try a bigger number or turning it off. I think you need to stop & restart apache for this to take effect.
>
> 3. How easy is it to take apache out of the loop and serve directly from Seaside?
> 4. Paul mentions moving some javascript - I looked at the audits tab in the Chrome developer tools and it said this about your page:
>
> Optimize the order of styles and scripts (3)
>
> The following external CSS files were included after an external JavaScript file in the document head. To ensure CSS files are downloaded in parallel, always include external CSS before external JavaScript.
> bootstrap.min.css
> bootstrap-responsive.min.css
> style.css
>
> so maybe moving that kavascript is something to try.
>
> Cheers,
> Bob
>
> P.S. I updated my squeak test to reuse sockets and still had no problem, so it looks more and more like something the browser is doing beyond just getting a bunch of files.
>
>
> On 11/27/12 2:34 PM, Tudor Girba wrote:
>> 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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>>>>>>
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>>
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