Hello Michael, Monday, March 11, 2002, 3:38:28 PM, you wrote:
I had a close problem once - then having many active connections (and so threads) mysql speed may degrade a lot because of scheduling and convergency problem. This does not explain the mysql lock itself, but may be the reason (i.e too many threads may make mysql to lock or crush because of GLIBC limits) The good solution for this would be to put OOPS behind of apache. This gives two positive issues: - your apache server will have much less children and so will require much less memory and will basically work faster. In my case the number of children have dropped from 150 to 16 and required memory from about 1G to 200M (I'm running very complicated PHP scripts) - you will need much less number of connections for mysql. In my case the number have dropped from about 500 connections from web server to 50, and load average on mysql server fell from 3.0-4.0 to 0.5-1.0. P.S Are you using mysql binary or version compiled with patched GLIBC if not the threads limit should be the cause. MW> Hi! Sam>> We have a very high volume site (3 million page views a day) that's run Sam>> on 16 Apache / PHP web servers & 2 MySQL servers. We are using PHP with Sam>> persistent connections. Each MySQL serves 8 web servers & is supposed to Sam>> act as a failover machine for the other group of 8 web servers. Sam>> Sam>> The failover won't work now as if one MySQL goes down the cost of the 8 Sam>> web servers switching over is so high the other MySQL locks up. Sam>> Sam>> Each Apache / PHP server takes up hundreds of connections even when Sam>> they're idle so we ran into the Linux connection limit of 1000 & had to Sam>> recompile to get past that. Sam>> Sam>> Our actual MySQL CPU useage is low but the goes when with the connection Sam>> overhead when starting up or failing over a bank of machines. Sam>> Sam>> We get a mysterious MySQL lockup once a week at the same day & time. MW> Could you please describe the lookup, exactly what happens ? MW> What does 'mysqladmin var ext' show when this happens? MW> What do you have in your log files ? Sam>> Questions : Sam>> Sam>> - Is our configuration of 2 sets of 8 Apache/PHP web servers & 1 MySQL Sam>> servers just not a good idea ? MW> This should not be a problem. Sam>> - Would we better off with FreeBSD ? MW> If you are running a CMP machine, then Linux preforms normally better MW> than FreeBSD. MW> To be able to give some recommendations we need to know more about MW> this setup. Sam>> - Is there anyone doing any similar setups with lots of web servers & a Sam>> few MySQLs ? MW> We have several hundred of paying support customers with this setup. Sam>> - Is there any way to get Apache / PHP to use fewer connections ? MW> Stevens Rousseys exellent answer should help you with this Sam>> We pay for MySQL support but haven't had much help from them. MW> I checked our support email archive, but couldn't find anything from MW> you or your company in it. MW> Could you please use our supportwizard interface to make a ticket of MW> this problem so that we can help you with it? MW> If you have already a ticket, please email me the ticket number so MW> that we can check this up. MW> Regards, MW> Monty -- Best regards, Peter mailto:[EMAIL PROTECTED] --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
