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I have a website with around 5000 visitors a day running since months.

The PC config is : 16G Core i5-750 1x2 To on Ubuntu Server 12.04

Even when I restart mysql server with service mysql restart, when I do a top, I can see over 200% CPU on mysqld.

I tried to see if there is any blocked request there with show processlist; and there's no blocked one.

Here is the content of /etc/mysql/my.cnf :

#
# The MySQL database server configuration file.
#
# You can copy this to one of:
# - "/etc/mysql/my.cnf" to set global options,
# - "~/.my.cnf" to set user-specific options.
#
# One can use all long options that the program supports.
# Run program with --help to get a list of available options and with
# --print-defaults to see which it would actually understand and use.
#
# For explanations see
# http://dev.mysql.com/doc/mysql/en/server-system-variables.html

# This will be passed to all mysql clients
# It has been reported that passwords should be enclosed with ticks/quotes
# escpecially if they contain "#" chars...
# Remember to edit /etc/mysql/debian.cnf when changing the socket location.
[client]
port            = 3306
socket          = /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket          = /var/run/mysqld/mysqld.sock
nice            = 0

[mysqld]
#
# * Basic Settings
#
user            = mysql
pid-file        = /var/run/mysqld/mysqld.pid
socket          = /var/run/mysqld/mysqld.sock
port            = 3306
basedir         = /usr
datadir         = /var/lib/mysql
tmpdir          = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking
#
# Instead of skip-networking the default is now to listen only on
# localhost which is more compatible and is not less secure.
#bind-address           = 127.0.0.1
#
# * Fine Tuning
#
key_buffer              = 16M
max_allowed_packet      = 16M
thread_stack            = 192K
thread_cache_size       = 8
# This replaces the startup script and checks MyISAM tables if needed
# the first time they are touched
myisam-recover         = BACKUP
#max_connections        = 100
#table_cache            = 64
#thread_concurrency     = 10
#
# * Query Cache Configuration
#
query_cache_limit       = 1M
query_cache_size        = 16M
#
# * Logging and Replication
#
# Both location gets rotated by the cronjob.
# Be aware that this log type is a performance killer.
# As of 5.1 you can enable the log at runtime!
#general_log_file        = /var/log/mysql/mysql.log
#general_log             = 1
#
# Error log - should be very few entries.
#
log_error = /var/log/mysql/error.log
#
# Here you can see queries with especially long duration
#log_slow_queries       = /var/log/mysql/mysql-slow.log
#long_query_time = 2
#log-queries-not-using-indexes
#
# The following can be used as easy to replay backup logs or for replication.
# note: if you are setting up a replication slave, see README.Debian about
#       other settings you may need to change.
#server-id              = 1
#log_bin                        = /var/log/mysql/mysql-bin.log
expire_logs_days        = 10
max_binlog_size         = 100M
#binlog_do_db           = include_database_name
#binlog_ignore_db       = include_database_name
#
# * InnoDB
#
# InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
# Read the manual for more InnoDB related options. There are many!
#
# * Security Features
#
# Read the manual, too, if you want chroot!
# chroot = /var/lib/mysql/
#
# For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
#
# ssl-ca=/etc/mysql/cacert.pem
# ssl-cert=/etc/mysql/server-cert.pem
# ssl-key=/etc/mysql/server-key.pem



[mysqldump]
quick
quote-names
max_allowed_packet      = 16M

[mysql]
#no-auto-rehash # faster start of mysql but no tab completition

[isamchk]
key_buffer              = 16M

#
# * IMPORTANT: Additional settings that can override those from this file!
#   The files must end with '.cnf', otherwise they'll be ignored.
#
!includedir /etc/mysql/conf.d/

Any ideas?

Davos
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  • 6

1 Answers1

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InnoDB Tables have their own settings.

For example:

innodb_buffer_pool_size = 10G # (adjust value here, 50%-70% of total RAM)

innodb_flush_log_at_trx_commit = 1 # may change to 2 or 0

innodb_flush_method = O_DIRECT

Take a look at this: https://www.percona.com/blog/2016/10/12/mysql-5-7-performance-tuning-immediately-after-installation/

and this: https://www.percona.com/blog/2014/01/28/10-mysql-performance-tuning-settings-after-installation/

and this: https://serverfault.com/questions/871585/mariadb-taking-up-100-200-cpu

You may try to update: https://askubuntu.com/questions/422612/installing-mysql-5-6-using-ppa

gpicchiarelli
  • 454
  • 6
  • 16
  • I tried adding `innodb_buffer_pool_size = 5G # (adjust value here, 50%-70% of total RAM) innodb_log_file_size = 256M innodb_flush_log_at_trx_commit = 1 # may change to 2 or 0 innodb_flush_method = O_DIRECT` and got `start: Job failed to start` while restarting `mysql`, it's probably linked to my `mysql version` which is older : `Ver 14.14 Distrib 5.5.54` – Davos Jul 29 '18 at 20:42
  • It fails on `innodb_log_file_size = 256M`, and if I put just the 3 others setting, the CPU is still going to more than 100% – Davos Jul 29 '18 at 20:55
  • Don't change the log file size... that requires removing the old logs, which are now the "wrong" size, and is probably more invasive than what you need to be doing at this point. – Michael - sqlbot Jul 29 '18 at 21:10
  • But is it 200% even when there is no load? – gpicchiarelli Jul 29 '18 at 22:23
  • @davos Any chance you can post requested information next week? Thanks – Wilson Hauck Aug 04 '18 at 18:04