The longer the thread the longer it takes to post replies to it

[tortyNet]

Hi,

we have some strange behavior on long running threads (6k+ answers 400+ pages) While the single thread pages render fine, it takes a very long time to post new answers to this kind of threads. Also it seems like the indexpages these threads live in take longer to render than indexpages where only threads with a few hundred replies exists. Once we close the topic an open a new one the problem is gone (posting instant, displaying index pages once the thead falls back to page 2) but this kind or solution does not feel right.

We are running version 5.4.5 - php 7.1 and mysql 5.6.
We use memcached as caching layer

Any idea what is going wrong here? Or known issue that long threads are slow? Any advice to fix this problem?

Thanks


Edit: Small update, index pages only take longer when logged in (as the cache does not kick in as on anonymous requests, i would guess)

[tortyNet]

Hmm I think we found something:

This query takes really long for what it is doing ->

SELECT `lastcontent`,`lastcontentid`,`lastcontentauthor`,`lastauthorid` FROM node  
WHERE `parentid` = 8 AND `showpublished` = 1 AND `showapproved` = 1 AND `contenttypeid` NOT IN (34,33,38) 
 ORDER BY `lastcontent` DESC, `lastcontentid` DESC
 LIMIT 1

Seems like this comes from node.php Problem here is that mysql cannot find a suitable index for this query and the more messages there are in a thread (or private messages in the system like in this case) the longer the query runs

You might want to add a new index to the database which in our case helped a lot with long running posts ... still the index pages are slow, but at least users can write answers again without waiting 20 - 30 seconds.

[Wayne Luke]

Any idea what is going wrong here? Or known issue that long threads are slow? Any advice to fix this problem?

It is a known issue and something we're working on. Part of it is memory issues. Part of it is processing. The way that vBulletin 5 works, that entire 6,000 posts needs to be loaded into memory every time someone looks at the page. There is a fix in 5.5.0 that should help with memory issues. This should allow the page to load better but not necessarily faster. We're working on the processing part of the equation but I don't have a time frame for a fix.

Right now, I would suggest using shorter topics.

[Wayne Luke]

You can also try adding the index in this topic - https://www.vbulletin.com/forum/foru...ce-improvement

However, this isn't tested and not fully supported.

[tortyNet]

Thanks for the info, thats basically the index we added to solve the posting timings. However index pages still render quite slow. Lets see if 5.5 brings any help here