mysql error number: 1040

[Jeff]

Started getting mySQL errors at 10:58 PM and am unable to access my forums right now:

Database error in vBulletin :

Link-ID == false, connect failed
mysql error: Too many connections

mysql error number: 1040

Date: Saturday 05th of January 2002 10:58:21 PM
Script: /forums/forumdisplay.php?forumid=12
Referer:

Edit: Sorry - Back online at 11:04.

[Jeff]

P.S. In the future I will try to not post a problem report for 15 minutes, but I'm just so used to everything but the mySQL servers having absolute 100% uptime at FutureQuest that it throws me when the SQL server has a problem. In fact I think that these mySQL errors are my only problem with anything on the FutureQuest servers in the last 12 months!

[Terra]

It is simply the nature of the beast with the MySQL servers as there are a pool of 255 connection slots available per server...

Occasionally, a doman's query can backlog the engine causing connections to stack up - or a spider can hit a vBulletin (or similar PHP/MySQL program) site so fast that it can temporarily overwhelm the server...

This is even true for a domain that is using a sole dedicated MySQL engine exclusively for their own use... The solution is within program rate limiting controls designed specifically to prevent this, as MySQL's primary purpose is low overhead - low latency SQL query processing... To add anything more to the MySQL engine is self defeating in that goal and destroys the freedom of exception handling that many programmers would rather control within their software... (Think failover and clusters with a common distributed data set)

Due to the design of MySQL, there is no easy way to prevent this or I would have done it long time ago... The only way to prevent it is to design and wedge in a frontside MySQL proxy - however this scenario has performance issues for which the cure is worse than the disease...

So, if you are using the MySQL server resources, you must come to the realization this condition _will_ happen and your code must properly handle the error... 9 out of 10 times, it will clear itself out in 5 minutes or less...

--
Terra
--just passing along the reality of things--
FutureQuest

<TAG [FAQ]: MySQL Connection Exhaustion>

[Terra]

To show you visually the MYSQL04 server operations efficiency for the last 26 hours:




These are internal graphs that I do make public from time to time as sometimes a picture is worth a thousand words...

That spike you see is what caused the connection problem... However, it is plain to see that our MYSQL04 engine is well within boundries and running a smooth as silk...

The rest I explained in my prior post...

--
Terra
--I promise that I read the articles as well--
FutureQuest

[Jeff]

Thanks as usual Terra,

That helps explain why MySQL is somewhat costly as well (compared to hosting a static site).

I always appreciate learning something