Slow loading of pages, especially images

pop

It might well be that the server is running slowly (if one can run slowly, that is). Is it short on memory or does it have other tasks that use much processing power or that provoke heavy disk access?

gwuk

pop
Hi, thanks for that. I'm told by the host provider that there is not undue load on the server. Also one of the pages that loads so slowly (in the example above) is a very simple page with small images. Other more complicated pages with larger images load ok

andi

Can you give us a link to an affected page?

gwuk

andi
Most of the pages are behind a password but I've made a simple page that is affected readable without a password
http://heynm.org.uk/GWTESTING/doku.php?id=wiki_administration:index

andi

Hmm, I can reproduce the problem on your server. However there are some oddities:

When I open the page you linked to, the problem happens
When I try to directly fetch an affected image in another browser tab while 1. is happening, it also stalls
When I try to directly fetch an affected image via wget while 1. is happening, it is downloaded immeadiately
Once 1. has settled, I can directly access the image immeadiately
Downloading the image and putting it into my local wiki causes no problems

To me it seems there is some kind of rate limiting going on. Whenever the server receives too many simultaneous requests (which happens when it requests multiple images) the server starts to throttle the connection. So maybe ask your provider again if they do any such thing (and consider switching to a better provider).

gwuk

andi ok, thank you for your help and advice, much appreciated. I will go back to the hosting provider.

pop

This is really odd.
Loading the page (http://heynm.org.uk/GWTESTING/doku.php?id=wiki_administration:index) for the first time is really fast and takes less than a second in a private browser window.
When that page is shown, reloading the page or calling another page through any of the links on the page will take exceedingly long. During the time from clicking the link until something visible happens, 25% of the processing power of all of the four processors in my computer is being used. This begins when I click the link and ends when the page finally is shown.
Also, the page apparently is not loaded all at once. Several of the icons used with the links on the page appear only after a while.
I am not qualified to debug your site, but I think the problem might be somehow related to some of the scripts in the page.
I don't recognize the layout of your Wiki. Are there any plugins which rely on client-side scripts?

gwuk

pop
It uses the menu plugin https://www.dokuwiki.org/plugin:menu
which on looking hasn't been updated for a long time so I wonder if this could be the problem

andi

pop I think the problem might be somehow related to some of the scripts in the page.

I tried disabling JavaScript but the result is the same, so I don't think it's anything client side.

gwuk

So, as a further update I have tried disabling that plugin but I still get exactly the same problem when I load the "media manager" page when it is trying to display thumbnail images for images within a namespace.

gerardnico

Why do you have a transfer-encoding http header with the value chunk ?

If I look at the HTTP request, there is only one. It seems that the whole download of the page is happening only with one connection.

Can we see the .htaccess file.

andi

gerardnico Why do you have a transfer-encoding http header with the value chunk ?

Chunked encoding is in HTTP since 1.1 and the webserver can decide to use it. Nothing weird there IMHO.

gerardnico If I look at the HTTP request, there is only one.

What do you mean by that? Where/how are you checking that? Chrome should open up to 6 concurrent connections to the same host but should reuse these connections since keepalive is enabled. Other browsers should have similar behaviour.

@gwuk what did your provider reply?

gerardnico

andi What do you mean by that?

Chrome Devtool ... Wireshark does not work on my system, I can't check on tcp level.

gwuk

andi
My hosting provider was recently taken over by another provider and they say I'm still hosted on the old servers which they have little ability to do diagnostics on. They are suggesting migrating to new servers but at increased cost.
I'm waiting to see if they will allow a temporary test on the newer servers before deciding

virk

What about to install a parallel wiki besides the existing one and by copying data/plugins from existing to parallel one to investigate the phenomenon?

gwuk

virk
Thanks the version I have been testing is a copy of the main wiki but on the same server.
I did try disabling all plugins + updating to latest version but still saw the problem

andi

Looking a bit more at the request behavior I notice that those slow loading requests succeed in 30s intervals which correlates with the standard PHP timeout.

requests in chrome

However it's not always that a fetch.php request will take long. The first fetch.php for wiki_administration:tick.png returns in a reasonable time of 274ms.

I still think there's something fishy going on at your provider and their answer of "we don't actually know what our servers do but please give us more money" does not spur confidence in their abilities.

gwuk

andi
Thank you again, I appreciate your help with investigating this.
I agree it does not inspire confidence in the hosting provider. I think what they are saying is that they have taken over my original provider but the actual hosting was done by a third party which they have limited access to. They want me to migrate to their own inhouse servers which are slightly more expensive but which they have more ability to provide diagnostics. They have agreed to migrate me at no extra cost until my current package expires which is almost a year away. There are some other advantages to me from moving as well so I will try this and if it doesn't help, consider moving to another provider. I'll post back an update when this has happened.

Global DokuWiki Links