The MySQL server creates the following threads:
Connection manager threads handle client connection requests on the network interfaces that the server listens to. On all platforms, one manager thread handles TCP/IP connection requests. On Unix, this manager thread also handles Unix socket file connection requests.
A signal thread handles all signals. This thread also normally handles alarms and calls process_alarm() to force timeouts on connections that have been idle too long.
InnoDB Main Thread/Background Thread, The main InnoDB thread is a special thread that just runs in a loop to do various kinds of work. In older versions of innodb it did just about everything, and that was often a source of problems. It was once responsible for keeping the transaction logs flushed as well as handling asynchronous io requests and much more. A stall in any number of places would cause the others to get far behind.
Since then many tasks handled by the main thread have been split out into separate threads, which means even if there's a stall in one, others can continue to function and help make sure the server keeps responding.
For InnoDB there will be additional read and write threads by default. The number of these are controlled by the innodb_read_io_threads and innodb_write_io_threads parameters.
On a master replication server, connections from slave servers are handled like client connections: There is one thread per connected slave.
On a slave replication server, an I/O thread is started to connect to the master server and read updates from it. An SQL thread is started to apply updates read from the master. These two threads run independently and can be started and stopped independently.
If the server is started with the --flush_time=val option, a dedicated thread is created to flush all tables every val seconds.
If the event scheduler is active, there is one thread for the scheduler, and a thread for each event currently running.
For more information go through MySQL Threads.
MySQL Internals, MySQL HighAvailability, MySQL Performance Tuning, MySQL Query Optimization, MySQL performance, MySQL Fabric, MySQL HA, MySQL Installation, MySQL Upgrade, InnoDB Performance Tuning, InnoDB Buffer Pool Size, MySQL Performance Tuning, MySQL ClusterMySQL Latest News, News and Events, MySQL Customers
Connection manager threads handle client connection requests on the network interfaces that the server listens to. On all platforms, one manager thread handles TCP/IP connection requests. On Unix, this manager thread also handles Unix socket file connection requests.
A signal thread handles all signals. This thread also normally handles alarms and calls process_alarm() to force timeouts on connections that have been idle too long.
InnoDB Main Thread/Background Thread, The main InnoDB thread is a special thread that just runs in a loop to do various kinds of work. In older versions of innodb it did just about everything, and that was often a source of problems. It was once responsible for keeping the transaction logs flushed as well as handling asynchronous io requests and much more. A stall in any number of places would cause the others to get far behind.
Since then many tasks handled by the main thread have been split out into separate threads, which means even if there's a stall in one, others can continue to function and help make sure the server keeps responding.
For InnoDB there will be additional read and write threads by default. The number of these are controlled by the innodb_read_io_threads and innodb_write_io_threads parameters.
On a master replication server, connections from slave servers are handled like client connections: There is one thread per connected slave.
On a slave replication server, an I/O thread is started to connect to the master server and read updates from it. An SQL thread is started to apply updates read from the master. These two threads run independently and can be started and stopped independently.
If the server is started with the --flush_time=val option, a dedicated thread is created to flush all tables every val seconds.
If the event scheduler is active, there is one thread for the scheduler, and a thread for each event currently running.
For more information go through MySQL Threads.
MySQL Internals, MySQL HighAvailability, MySQL Performance Tuning, MySQL Query Optimization, MySQL performance, MySQL Fabric, MySQL HA, MySQL Installation, MySQL Upgrade, InnoDB Performance Tuning, InnoDB Buffer Pool Size, MySQL Performance Tuning, MySQL ClusterMySQL Latest News, News and Events, MySQL Customers
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