MySQL takes up too much memory solution

Preface

For some petty bourgeoisie players , The number of servers and memory are often very limited , My personal server configuration is 2 nucleus 4G5M.

4G Memory for Java Game player , It's really not big , Open several middleware + Their own micro services are really crowded , Then spread it MySQL This big enemy . I'm on this machine MySQL Only a few M Memory （ Although I don't use it very much , But this machine MySQL It's really on ）：

And the server accounts for 400M, In fact, there is no throughput , Just play by yourself , This memory occupation is really a little unbearable ...

Solution

Learned that you can reduce by modifying the configuration MySQL Memory footprint , I tried , And recorded . Because I have two servers at the same time , One is equipped with windows service 2016, Another one is equipped with CentOS7, The situation of both sets is similar , So make two records at the same time , For your reference .

Find the configuration file

Windows Service 2016

The default location of the configuration file is C:\ProgramData\MySQL\MySQL Server 8.0\my.ini, If there is any modification , Find out according to your actual situation .

CentOS7

The default path of the configuration file is /etc/my.cnf, If there is any modification , Find out according to your actual situation .

Modify the configuration file

Windows It can be used Ctrl + F To search ,Linux It can be used ‘/key’ To search , If not, you can refer to Baidu .

There are three things we need to find and modify ：

1. find table_definition_cache, Let's change it to 400

   The official explanation is ： The number of table definitions that can be stored in the definition cache （ come from .frm file ）. If you use a large number of tables , You can create a large table definition cache to speed up the opening of tables . Different from ordinary table caching , The table definition cache takes up less space , And do not use file descriptors . The minimum and default values are 400.

2. find table_open_cache, Let's change it to 256

   MySQL Every time I open a watch , Will read in some data to table_open_cache In cache , When MySQL When no corresponding information is found in this cache , Will go to the disk to read .

   The official explanation is ： Number of open tables for all threads . Increasing this value will increase mysqld Number of file descriptors required . therefore , You have to make sure that at [mysqld safe] Partial variables “open files limit” Set the number of files allowed to be opened to at least 4096.

3. find performance_schema , It is amended as follows off

   If you can't find this , Directly add performance_schema = off that will do .

   Used to monitor MySQL server Resource consumption in a lower level of running process 、 Resource waiting, etc , You can save money after closing , Will not make server Your behavior changes .

Save and exit after modification .

restart MySQL

Windows Service 2016

Start the console as an administrator , Input net stop mysql, And then you type in net start mysql.

After restart, it still takes 62M.

CentOS7

Console input service mysqld restart You can restart .

If not , You can try /etc/init.d/mysqld restart This instruction .

Occupied after restart 92M, Than Windows That one is more .

Postscript

In this way, it can really reduce mysql Memory footprint , But I'm just trading performance for memory , If the throughput requirements are relatively high , It certainly cannot be modified directly like this , It has to be adjusted according to the actual request .