Red Hat Bugzilla – Bug 111413
MySQL using exessive processing power and sluggish queries
Last modified: 2007-11-30 17:06:59 EST
From Bugzilla Helper: User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Description of problem: The MySQL version in question was downloaded from the Red Hat Network Enterprise ES 3 Extras channel. This MySQL version seems to be using exessive processing power and queries seem sluggish compared to the install running on a RH7.2 machine we use. (default 3.23.58 rpm install) We had a big web-site on our 7.2 machine that was quite heavy on MySQL. After moving to our new ES3 server MySQL uses a lot more processing power, even though the system has double the RAM, processing power e.t.c The system spec is: 2.8Ghz P4 2GB PC2700 DDR RAM 2x 120GB Western Digital IDE Hard Disks Asus P4P800-VM "i865G" Motherboard Using TOP and PS commands, I also notice that there is never more than 1 MySQL process in the process list. Im not sure if this is normal, as on the 7.2 machines there are always many MySQL processes in the list. The URL supplied is a screenshot of TOP showing the big processor usage. Note the time this process has been running, I guess due to it being the only process handling MySQL requests. Version-Release number of selected component (if applicable): mysql-server-3.23.58-1 How reproducible: Always Steps to Reproduce: 1. Run queries on a moderate to large database Actual Results: MySQL uses a lot of processing power, only one process seems to handle all of the requests. Expected Results: mysql processes using less CPU power, more than one MySQL process in the process list. Additional info:
I'm really not sure what you expect us to do here. You have not included any code samples of what is slowing down. MySQL 3.23.58 is not, from a modification point of view, terribly different than prior 3.23 releases (ie. it's just a bug fix release). I'd take a look at any performance tuning you did on 7.2 and port it to ES. You may also want to take a look at the performance tips listed on the MySQL web site (www.mysql.com).
I believe the behavior this gentleman is concerned about is that mysql is running with a single process. Previous versions had forked several mysqld processes. I'm seeing the same thing on my database server. Code samples are not really relevant - I'm essentially running a dual process (actually quad if you count the hyperthreaded processors) in single processor mode, with one thread of mysqld. Essentially, mysqld appears to have been started with the "--one- thread" option but that option isn't being passed on the command line for startup... So, off to see if I can figure out what is going on...
Arg, nevermind - they're there, they are threads, though so they don't show up with normal ps auxw output :) Should have checked mysqladmin extended-status first...