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I have an insane usage of cpu mysqld +600% here is the file my cnf

# Example MySQL config file for medium systems.
#
# This is for a system with little memory (32M - 64M) where MySQL plays
# an important part, or systems up to 128M where MySQL is used together with
# other programs (such as a web server)
#
# You can copy this file to
# /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options (in this
# installation this directory is /opt/lampp/var/mysql) or
# ~/.my.cnf to set user-specific options.
#
# In this file, you can use all long options that a program supports.
# If you want to know which options a program supports, run the program
# with the "--help" option.

# The following options will be passed to all MySQL clients
[client]
#password   = your_password
port        =3306
socket      =/opt/lampp/var/mysql/mysql.sock

# Here follows entries for some specific programs

# The MySQL server
default-character-set=utf8mb4
[mysqld]
user=mysql
port=3306
socket      =/opt/lampp/var/mysql/mysql.sock

key_buffer=64M
max_allowed_packet=10M
table_open_cache=64
sort_buffer_size=2M
net_buffer_length=8K
read_buffer_size=256K
read_rnd_buffer_size=512K
myisam_sort_buffer_size=8M
query_cache_type=1
query_cache_limit=512K
query_cache_size=0
query_cache_min_res_unit=256
innodb_thread_concurrency=0
innodb_log_file_size=128M


# Custom changes
max_connections     = 400
query_cache_limit   = 32M
query_cache_size    = 0
innodb_buffer_pool_size = 20G
innodb_buffer_pool_instances = 10
innodb_log_file_size    = 1G
innodb_log_buffer_size  = 5G
innodb_file_per_table   = 1
innodb_open_files       = 400
innodb_io_capacity      = 1000
innodb_io_capacity_max  = 40000
innodb_flush_method     = O_DIRECT
innodb_read_io_threads  = 8
innodb_write_io_threads = 4
thread_cache_size       = 100
innodb_lru_scan_depth   = 100
innodb_read_io_threads  = 64
innodb_write_io_threads = 64
open_files_limit        = 4096
table_open_cache        = 2048
join_buffer_size        = 128K
read_buffer_size        = 128K
log_warnings            = 2
key_cache_age_threshold = 64800
innodb_change_buffer_max_size = 10
max_write_lock_count    = 16





# End custom changes

# Where do all the plugins live
plugin_dir=/opt/lampp/lib/mysql/plugin/

# Don't listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the "enable-named-pipe" option) will render mysqld useless!
# 
#skip-networking

# Replication Master Server (default)
# binary logging is required for replication
# log-bin deactivated by default since XAMPP 1.4.11
#log-bin=mysql-bin

# required unique id between 1 and 2^32 - 1
# defaults to 1 if master-host is not set
# but will not function as a master if omitted
server-id   =1

# Replication Slave (comment out master section to use this)
#
# To configure this host as a replication slave, you can choose between
# two methods :
#
# 1) Use the CHANGE MASTER TO command (fully described in our manual) -
#    the syntax is:
#
#    CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
#    MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
#
#    where you replace <host>, <user>, <password> by quoted strings and
#    <port> by the master's port number (3306 by default).
#
#    Example:
#
#    CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,
#    MASTER_USER='joe', MASTER_PASSWORD='secret';
#
# OR
#
# 2) Set the variables below. However, in case you choose this method, then
#    start replication for the first time (even unsuccessfully, for example
#    if you mistyped the password in master-password and the slave fails to
#    connect), the slave will create a master.info file, and any later
#    change in this file to the variables' values below will be ignored and
#    overridden by the content of the master.info file, unless you shutdown
#    the slave server, delete master.info and restart the slaver server.
#    For that reason, you may want to leave the lines below untouched
#    (commented) and instead use CHANGE MASTER TO (see above)
#
# required unique id between 2 and 2^32 - 1
# (and different from the master)
# defaults to 2 if master-host is set
# but will not function as a slave if omitted
#server-id       = 2
#
# The replication master for this slave - required
#master-host     =   <hostname>
#
# The username the slave will use for authentication when connecting
# to the master - required
#master-user     =   <username>
#
# The password the slave will authenticate with when connecting to
# the master - required
#master-password =   <password>
#
# The port the master is listening on.
# optional - defaults to 3306
#master-port     =  <port>
#
# binary logging - not required for slaves, but recommended
#log-bin=mysql-bin


# Point the following paths to different dedicated disks
#tmpdir     = /tmp/     
#log-update     = /path-to-dedicated-directory/hostname

# Uncomment the following if you are using BDB tables
#bdb_cache_size = 4M
#bdb_max_lock = 10000

# Comment the following if you are using InnoDB tables
#skip-innodb
innodb_data_home_dir=/opt/lampp/var/mysql/
innodb_data_file_path=ibdata1:10M:autoextend
innodb_log_group_home_dir=/opt/lampp/var/mysql/
# You can set .._buffer_pool_size up to 50 - 80 %
# of RAM but beware of setting memory usage too high
#innodb_buffer_pool_size=512M
# Deprecated in 5.6
#innodb_additional_mem_pool_size = 2M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size=5M
#innodb_log_buffer_size=8M
innodb_flush_log_at_trx_commit=1
innodb_lock_wait_timeout=50

character-set-server=utf8mb4
collation-server=utf8mb4_general_ci

[mysqldump]
max_allowed_packet=10M

[mysql]
# Remove the next comment character if you are not familiar with SQL
#safe-updates

[isamchk]
key_buffer=20M
sort_buffer_size=20M
read_buffer=2M
write_buffer=2M

[myisamchk]
key_buffer=20M
sort_buffer_size=20M
read_buffer=2M
write_buffer=2M

[mysqlhotcopy]


!include /opt/lampp/mysql/my.cnf 

                                                                                             

I don't know if this is the right code to use for better performance, I'm using wordpress. I'm experiencing some problems with my mysql server When I run top command, it sais that mysql process has taken over 350-600% of CPU I'm running ubuntu 18.04 with 32 GB RAM

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  • Can't tune away performance problems. See this for identifying the 'worst' query and presenting it here for assistance: mysql.rjweb.org/doc.php/mysql_analysis#slow_queries_and_slowlog See this for a speedup specifically tailored to WP: mysql.rjweb.org/doc.php/… – Rick James Sep 29 '20 at 22:26
  • Additional information request. # cores, any SSD or NVME devices on MySQL Host server? Post on pastebin.com and share the links. From your SSH login root, Text results of: B) SHOW GLOBAL STATUS; after minimum 24 hours UPTIME C) SHOW GLOBAL VARIABLES; D) SHOW FULL PROCESSLIST; E) complete MySQLTuner report AND Optional very helpful information, if available includes - htop OR top for most active apps, ulimit -a for a Linux/Unix list of limits, iostat -xm 5 3 for IOPS by device and core/cpu count, for server workload tuning analysis to provide suggestions. – Wilson Hauck Oct 7 '20 at 14:18
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apt install mytop and look at what queries are running that are eating all your CPU. High CPU usage is a symptom of bad queries rather than bad configuration. Or you are just running a very intensive workload.

You also have an awful lot of configuration deviations from default. Unless you know exactly what you are doing and why, the only thing you should be touching is innodb_buffer_pool_size.

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