How long is too long?

[Cedric_FP]

I run a VB forum, version 3.67, and I was wondering, how long can a thread be before it really starts to have adverse effects on forum performance?

From what I understand about PHPBB, any thread above 100 pages can start to hamper performance as the forum has to queue up the requests of all posts within the thread, or something to that effect.

Is this the same with VB? I have several very active threads with well over 500 pages (20 posts to the page) and one which is around 2200 pages long and around 46,000 replies.

Is this too long? Should I lock the thread and start a new one to avoid database stress?

Thank you.

[EWGF]

From what I've heard, it's best to keep threads under 1000 replies.

[Cedric_FP]

From what I've heard, it's best to keep threads under 1000 replies.

Wow, 1000 replies? That seems awfully short, doesn't it?

[Fireproof]

Interesting discussion. I run a fitness forum and we have members' training journals that have well over 2,000 posts in it. So far so good.

[EWGF]

Wow, 1000 replies? That seems awfully short, doesn't it?

I used to moderate on a big-board and the admin said we had to close threads with 1000 or more replies. Although, the server of that site was never that great and currently it always shows the "the server is too busy" message.

Perhaps it's more server-related..

[Cedric_FP]

I used to moderate on a big-board and the admin said we had to close threads with 1000 or more replies. Although, the server of that site was never that great and currently it always shows the "the server is too busy" message.

Perhaps it's more server-related..

Perhaps. I have noticed some slow downs in my boards, particularly when many are viewing the 46,000 reply thread, but then again, like you mentioned with the forum you moderated, I don't have a particularly stellar host, though I've never had issues with "server too busy" error messages before.

Over at some other forums I frequent, which also use VB, they close threads after 1k replies as well.

I wonder if one of the developers could give some concrete advice as to how short/long threads should be kept.

[Cedric_FP]

Perhaps. I have noticed some slow downs in my boards, particularly when many are viewing the 46,000 reply thread, but then again, like you mentioned with the forum you moderated, I don't have a particularly stellar host, though I've never had issues with "server too busy" error messages before.

Over at some other forums I frequent, which also use VB, they close threads after 1k replies as well.

I wonder if one of the developers could give some concrete advice as to how short/long threads should be kept.

No official word from the devs?

[Steve Machol]

The Devs don't normally read the support forums. There is no solid recommendation because this depends on the server more than anything else. If this is a concern, then perhaps you should close that thread.

[Xodus]

It shouldn't add any more stress than a 3 page thread. I'm 99% sure they use a LIMIT sql command where they only pull the postid's that they need.

[Cedric_FP]

It shouldn't add any more stress than a 3 page thread. I'm 99% sure they use a LIMIT sql command where they only pull the postid's that they need.

I see. This is reassuring. Thanks.

[Wayne Luke]

From what I've heard, it's best to keep threads under 1000 replies.

http://www.vbulletin.com/forum/showthread.php?t=1091

Has over 2500 replies. I have my viewing set to 100 posts per page and don't have any problem viewing that thread.

I think we have a thread with over 10,000 replies in the archive somewhere.

[Cedric_FP]

The Devs don't normally read the support forums. There is no solid recommendation because this depends on the server more than anything else. If this is a concern, then perhaps you should close that thread.

Ahh, therein lies the problem. The thread has become quite an icon within the community, and it would be such a shame to close it.

http://www.vbulletin.com/forum/showthread.php?t=1091

Has over 2500 replies. I have my viewing set to 100 posts per page and don't have any problem viewing that thread.

I think we have a thread with over 10,000 replies in the archive somewhere.

This is reassuring also. If VB.com runs threads this long, then I certainly can

[PSS]

It shouldn't add any more stress than a 3 page thread. I'm 99% sure they use a LIMIT sql command where they only pull the postid's that they need.

Wrong.

All the posts will still need to be sorted before certain LIMIT range can be found by mysql engine. In order to use indexes and caches effectively you would have to have enough RAM and my.cnf settings that use it. The less the thread is active, the more likely it is dropped from active caches and it means it gets really slow. If thread is active and you have set caches big enough it could be instant.

Simply said: when you reboot the server (not mysql) the disk and mysql caches are reset which means the long threads open very slowly. After that, if there is activity, they open fast.

I have many threads which are 20,000 up to 57,000 posts and initial opening of those take about 700-1000 posts a second with a server that has Dual Woodcrests, database on separate 15k rpm SAS-SCSI, 64-bit MySQL 5, memcached+memcache, APC, Litespeed Enterprise 3.2. I'll have to do some EXPLAIN with those queries but I'm sure the time is spend to sorting with temporary tables and table scan. After first load even 50,000 post thread opens immediately because it is indexed and cached.

Is there anything that can speed up the initial load time? Good question Disk speed, larger indexes, split queries? I'll have to benchmark a bit more.

[PSS]

Contd:
I added indexes mentioned in http://www.vbulletin.com/forum/showthread.php?t=218599.
Initial large thread opening speed went up to 1200-3500 posts/second. Not bad.