(mysql.info) slave-io-thread-states

Info Catalog

(mysql.info) master-thread-states

(mysql.info) replication-implementation-details

(mysql.info) slave-sql-thread-states

 
 6.3.2 Replication Slave I/O Thread States
 -----------------------------------------
 
 The following list shows the most common states you see in the `State'
 column for a slave server I/O thread.  This state also appears in the
 `Slave_IO_State' column displayed by `SHOW SLAVE STATUS', so by using
 that statement, you can get a good view of what is happening.
 
    * `Connecting to master'
 
      The thread is attempting to connect to the master.
 
    * `Checking master version'
 
      A state that occurs very briefly, after the connection to the
      master is established.
 
    * `Registering slave on master'
 
      A state that occurs very briefly after the connection to the
      master is established.
 
    * `Requesting binlog dump'
 
      A state that occurs very briefly, after the connection to the
      master is established. The thread sends to the master a request
      for the contents of its binary logs, starting from the requested
      binary log filename and position.
 
    * `Waiting to reconnect after a failed binlog dump request'
 
      If the binary log dump request failed (due to disconnection), the
      thread goes into this state while it sleeps, then tries to
      reconnect periodically. The interval between retries can be
      specified using the -master-connect-retry option.
 
    * `Reconnecting after a failed binlog dump request'
 
      The thread is trying to reconnect to the master.
 
    * `Waiting for master to send event'
 
      The thread has connected to the master and is waiting for binary
      log events to arrive. This can last for a long time if the master
      is idle. If the wait lasts for `slave_read_timeout' seconds, a
      timeout occurs. At that point, the thread considers the connection
      to be broken and makes an attempt to reconnect.
 
    * `Queueing master event to the relay log'
 
      The thread has read an event and is copying it to the relay log so
      that the SQL thread can process it.
 
    * `Waiting to reconnect after a failed master event read'
 
      An error occurred while reading (due to disconnection). The thread
      is sleeping for `master-connect-retry' seconds before attempting
      to reconnect.
 
    * `Reconnecting after a failed master event read'
 
      The thread is trying to reconnect to the master. When connection
      is established again, the state becomes `Waiting for master to
      send event'.
 
    * `Waiting for the slave SQL thread to free enough relay log space'
 
      You are using a non-zero `relay_log_space_limit' value, and the
      relay logs have grown large enough that their combined size
      exceeds this value. The I/O thread is waiting until the SQL thread
      frees enough space by processing relay log contents so that it can
      delete some relay log files.
 
    * `Waiting for slave mutex on exit'
 
      A state that occurs briefly as the thread is stopping.
 

Info Catalog

(mysql.info) master-thread-states

(mysql.info) replication-implementation-details

(mysql.info) slave-sql-thread-states