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(mysql.info)MySQL threads

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MySQL Threads
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The MySQL server creates the following threads:

   * The TCP/IP connection thread handles all connection requests and
     creates a new dedicated thread to handle the authentication and
     and SQL query processing for each connection.

   * On Windows NT there is a named pipe handler thread that does the
     same work as the TCP/IP connection thread on named pipe connect
     requests.

   * The 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.

   * If `mysqld' is compiled with `-DUSE_ALARM_THREAD', a dedicated
     thread that handles alarms is created.  This is only used on some
     systems where there are problems with `sigwait()' or if one wants
     to use the `thr_alarm()' code in ones application without a
     dedicated signal handling thread.

   * If one uses the `--flush_time=#' option, a dedicated thread is
     created to flush all tables at the given interval.

   * Every connection has its own thread.

   * Every different table on which one uses `INSERT DELAYED' gets its
     own thread.

   * If you use `--master-host', a slave replication thread will be
     started to read and apply updates from the master.

`mysqladmin processlist' only shows the connection, `INSERT DELAYED',
and replication threads.