MySQL/MariaDB出现'THREAD_CONCURRENCY' is deprecated and will be removed in a future release.那是由于MySQL 5.7 THREAD_CONCURRENCY已经被移除。

The deprecated thread_concurrency system variable has been removed

调整操作：

service mysql stop

然后将 /etc/my.cnf 中的 thread_concurrency = 8 改为 #thread_concurrency = 8，再启动MySQL：

service mysql start

随便分享个 my.cnf，适用于MariaDB 10.1、MySQL 5.6 & 5.7，当前服务器是：CentOS 8 x86_64、2G内存、MariaDB 10.1。

# Example MariaDB config file for medium systems.
#
# This is for a system with little memory (32M - 64M) where MariaDB plays
# an important part, or systems up to 128M where MariaDB is used together with
# other programs (such as a web server)
#
# MariaDB programs look for option files in a set of
# locations which depend on the deployment platform.
# You can copy this option file to one of those
# locations. For information about these locations, do:
# 'my_print_defaults --help' and see what is printed under
# Default options are read from the following files in the given order:
# More information at: http://dev.mysql.com/doc/mysql/en/option-files.html
#
# 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 MariaDB clients
[client]
#password	= your_password
port		= 3306
socket		= /var/lib/mysql/mysql.sock

# Here follows entries for some specific programs

# The MariaDB server
[mysqld]
port		= 3306
socket		= /var/lib/mysql/mysql.sock
skip-external-locking
key_buffer_size = 16M
max_allowed_packet = 1M
table_open_cache = 64
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 8M
thread_cache_size = 8
query_cache_size= 16M
# Try number of CPU's*2 for thread_concurrency
#thread_concurrency = 8
default-storage-engine=myisam
#innodb_use_sys_malloc = 0
#innodb_force_recovery=1

# Point the following paths to different dedicated disks
#tmpdir		= /tmp/

# 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=mysql-bin

# binary logging format - mixed recommended
binlog_format=mixed

# 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=
  
   , MASTER_PORT=
   
    , # MASTER_USER=
    
     , MASTER_PASSWORD=
     
       ; # # where you replace 
      
       , 
       
        , 
        
          by quoted strings and # 
         
           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 = 
          
            # # The username the slave will use for authentication when connecting # to the master - required #master-user = 
           
             # # The password the slave will authenticate with when connecting to # the master - required #master-password = 
            
              # # The port the master is listening on. # optional - defaults to 3306 #master-port = 
             
               # # binary logging - not required for slaves, but recommended #log-bin=mysql-bin # Uncomment the following if you are using InnoDB tables innodb_data_home_dir = /var/lib/mysql innodb_data_file_path = ibdata1:10M:autoextend innodb_log_group_home_dir = /var/lib/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 = 16M 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 [mysqldump] quick max_allowed_packet = 16M [mysql] no-auto-rehash # Remove the next comment character if you are not familiar with SQL #safe-updates [myisamchk] key_buffer_size = 20M sort_buffer_size = 20M read_buffer = 2M write_buffer = 2M [mysqlhotcopy] interactive-timeout