Recent site performance issues

[Karlos]

Notice

The cache is activated again for a third round of testing after last night. If you aren't logged in, don't be surprised when pages don't seem to update or if visiting a thread that on the main page claims has no new posts suddenly has a bunch - it's all down to when the cached version of a given page was saved. The cache is "dumb" for a reason - tying to invalidate cached pages on the basis that a linked page changed would require code that would defeat the entire point of trying to reduce server load.

If, when you log in, something isn't right, then please flag it up.

Only the main index, forum index and thread displays have any caching.

[Karlos]

I wonder if the gibberish was gz compressed content. The proxy should be telling the site not to accept this content encoding type - the cache has been written to serve both kinds of data (though it is always stored compressed).

Amusingly enough, I had serious delays just now, but my other "incognito" guest session was perfectly fast

[Karlos]

When you log in, you will be subject to any db-induced delays. When you aren't, you'll probably find it a lot faster provided the cache is still warm. Unless you are the unlucky one that requests a page that has timed out and needs to be regenerated

[Karlos]

Well ... that was interesting.  I submitted my last post and sat at 228KB / 228KB for about three minutes before the rest of the webpage finished downloading to my machine.

---
redfox

The kind of bugs I am looking for just now are things like "Becoming Piru", which is indicative of a serious bug in the cache system.

The site crawling like a wounded snail after you logged in is basically down to the DB server being too busy to respond to vBulletin's queries. Serving cached pages doesn't actually hit vBulletin at all, let alone the DB.

[Karlos]

If the problem can be fixed "by throwing hardware at it", drop me a PM... I've got a big stack'o'servers looking at me daily begging for a decent job...

You should talk to the owner, I'm just the guy with duct tape :lol:

[Karlos]

@Karlos

A few moments ago I tried to logout and eventually timed out.

OWB Requester contents as follows ...

Loading http://www.amiga.org/forums/login.php?do=logout&logouthash=1310416568-ec38b8e5174139829ab680a7dd065b55c7469090 failed!
Failure when receiving data from the peer
Please check the correct address for typing errors such as ww.example.com instead of http://www.example.com
If you are unable to load any pages, check your computer's network connection.
If your computer or network is protected by a firewall or proxy, make sure that OWB is permitted to access the Web.


Is this also due to DB server being too busy?

---
redfox

Very likely, unfortunately. Absolutely every page you try to access (including the logout one) results in several DB queries that if it's very busy can end up in a queue and you wait and wait. However, if the db server is feeling particularly bitchy, it just drops the connection to the application (or prevents the application from opening it in the first place) and then you get a proper 500 error, which may or may not be intercepted by vBulletin's error handler and if so, you get vB's "Database Error" page.

[Karlos]

So, anybody found themselves logged in as anybody else yet?

If not, I may leave the cache enabled overnight...

[Karlos]

Unfortunately, it seems the cache mechanism just isn't going to function well enough without a lot of additional work. Some folks couldn't log in and the cache got polluted with IP ban notifications caused when something unwelcome tried to crawl the site meaning all and sundry were suddenly shocked to see they'd been IP banned.

So, we're back to square one.

[Karlos]

Karlos,

Before I forget it (and sorry to be off-topic), if the "top" stats on the front page are slamming the server, I honestly don't think anyone here would even miss them if you went into the Admin and killed those blocks altogether.

I've left those cached (updates every 15mins) as they have no dependency on the viewer being logged in or out.