By default, MySQL using one thread to handle each connection to execute queries. As more client connections, more threads are created. Performance will degrades because of context switching, memory usage, resouce contention. A thread pool will reduces the creation of theads and improves performance on high concurrency scane. MySQL Enterprise provides a thread pool plugin, and some thirdpart fork like percona server, mariadb also provides this feature. But if you are using MySQL Community, this plugin will helps.

CAUTION:

mysql version >= 5.6.20 is REQUIRED

mysql plugins MUST be built using the same version of the source code and the same build arguments. If mysqld is built as a debug version without cmake parameter -DBUILD_CONFIG, the parameter must not be added when compiling plugins.

First, compile the plugin and install in to plugin dir

cp -r src /path/to/mysql-src/plugin/threadpool
cd /path/to/mysql-src
cmake . -DBUILD_CONFIG=mysql_release
cd plugin/threadpool
make
make install

Then, load the plugin into mysql

mysql> INSTALL PLUGIN THREADPOOL SONAME 'threadpool.so';