| Bug #16885 | MySQL 3.23.58 under Fedora fails to support multi-processors... | ||
|---|---|---|---|
| Submitted: | 29 Jan 2006 22:53 | Modified: | 9 Feb 2006 13:15 |
| Reporter: | Ryan Barclay | Email Updates: | |
| Status: | Not a Bug | Impact on me: | |
| Category: | MySQL Server | Severity: | S5 (Performance) |
| Version: | 3.23.58 | OS: | Linux (Linux - Fedora Core 2) |
| Assigned to: | CPU Architecture: | Any | |
[30 Jan 2006 9:29]
Valeriy Kravchuk
Thank you for a problem report. MySQL server is a single multi-threaded process. So, the task to spread its threads over processors is up to the OS scheduler. Please, send the my.cnf file content that leads to failure upon startup.
[30 Jan 2006 12:28]
Ryan Barclay
Thanks for the reply. Here is my my.cnf: ------------- [root@web2 root]# tail /etc/my.cnf [mysql.server] user=mysql basedir=/var/lib [safe_mysqld] err-log=/var/log/mysqld.log pid-file=/var/run/mysqld/mysqld.pid [client] socket=/home/virtual/FILESYSTEMTEMPLATE/.mysqlsock/mysql.sock ------------- When I add the line "thread_concurrency = 4" or any other number, MySQL service fails to start.
[9 Feb 2006 13:15]
Valeriy Kravchuk
If you want to set thread_concurrency, do it properly, according to the manual of version 3.23 (http://dev.mysql.com/doc/refman/4.1/en/server-system-variables.html etc.): openxs@suse:~/dbs/3.23> cat var/my.cnf [mysqld] set-variable = thread_concurrency=4 With this setting your 3.23.58 will start successfully, although, this server variable has a default value of 10 and it seems it is ignored on Linux (used for Solaris). Your "top" results show that all your 4 CPUs are equally loaded and used, so I see no evidence of not supporting multiple CPUs in this report.
Description: I'm running MySQL 3.23.58 with Fedora core 2 on a Dual Xeon system. I have quite a few busy websites that use the MySQL server, and noticed that my version of MySQL only runs one instance and uses 99% of the CPU that it's running on at peak times and only on one CPU with one instance. I would like to get several instances of MySQL running, like my apache does for PHP pages in module mode. Is it possible? I've tried adding the "thread_concurrency" setting to my my.cnf but after that MySQL fails to start. Here is a dump of the top command: --------------- [root@web2 root]# top 22:53:22 up 4 days, 5:09, 1 user, load average: 1.37, 1.68, 1.94 146 processes: 136 sleeping, 7 running, 3 zombie, 0 stopped CPU states: cpu user nice system irq softirq iowait idle total 142.0% 0.0% 58.0% 0.0% 0.0% 0.0% 199.2% cpu00 33.5% 0.0% 14.7% 0.0% 0.0% 0.0% 51.6% cpu01 33.5% 0.0% 12.6% 0.0% 0.0% 0.0% 53.7% cpu02 37.0% 0.0% 15.8% 0.0% 0.0% 0.0% 47.1% cpu03 38.1% 0.0% 14.9% 0.0% 0.0% 0.0% 46.9% Mem: 2068368k av, 1906936k used, 161432k free, 0k shrd, 98068k buff 901784k active, 897116k inactive Swap: 4096532k av, 62336k used, 4034196k free 1317276k cached PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND 11717 mysql 15 0 17432 17M 2648 S 70.2 0.8 81:41 2 mysqld 23657 root 17 0 1260 1260 820 R 1.7 0.0 0:00 1 top 2177 root 16 0 10660 1148 1072 S 0.3 0.0 0:42 0 MailScanner 22 root 15 0 0 0 0 SW 0.1 0.0 5:44 0 kjournald 638 root 15 0 0 0 0 SW 0.1 0.0 11:14 3 kjournald 639 root 15 0 0 0 0 SW 0.1 0.0 6:29 1 kjournald 12088 root 15 0 920 920 520 S 0.1 0.0 0:10 1 exclog 1 root 16 0 400 364 348 S 0.0 0.0 0:12 0 init 2 root RT 0 0 0 0 SW 0.0 0.0 0:00 0 swapper 3 root RT 0 0 0 0 SW 0.0 0.0 0:00 1 swapper 4 root RT 0 0 0 0 SW 0.0 0.0 0:00 2 swapper 5 root RT 0 0 0 0 SW 0.0 0.0 0:00 3 swapper 6 root 15 0 0 0 0 SW 0.0 0.0 0:00 0 keventd 7 root 34 19 0 0 0 SWN 0.0 0.0 0:01 0 ksoftirqd/0 8 root 34 19 0 0 0 SWN 0.0 0.0 0:00 1 ksoftirqd/1 9 root 34 19 0 0 0 SWN 0.0 0.0 0:00 2 ksoftirqd/2 10 root 34 19 0 0 0 SWN 0.0 0.0 0:00 3 ksoftirqd/3 12 root 25 0 0 0 0 SW 0.0 0.0 0:00 0 bdflush 11 root 15 0 0 0 0 SW 0.0 0.0 2:02 3 kswapd 13 root 15 0 0 0 0 SW 0.0 0.0 3:49 1 kupdated 14 root 25 0 0 0 0 SW 0.0 0.0 0:00 0 mdrecoveryd 73 root 17 0 0 0 0 SW 0.0 0.0 0:00 0 khubd 637 root 16 0 0 0 0 SW 0.0 0.0 0:00 3 kjournald 1714 root 16 0 360 352 300 S 0.0 0.0 0:17 1 irqbalance 1797 root 16 0 576 552 532 S 0.0 0.0 0:22 0 syslogd ---- I have included the first part of the top command. There is only ONE instance of mysqld running, even in the text not included above. How to repeat: Add the "thread_concurrency" setting to my my.cnf but after that MySQL fails to start.