The following list shows the most common states you may see in
State column for the master's
Binlog Dump thread. If you see no
Binlog Dump threads on a master server, this
means that replication is not running—that is, that no
slaves are currently connected.
The thread has finished reading a binary log file and is opening the next one to send to the slave.
The thread has read all outstanding updates from the binary logs and sent them to the slave. The thread is now idle, waiting for new events to appear in the binary log resulting from new updates occurring on the master.
Binary logs consist of events, where an event is usually an update plus some other information. The thread has read an event from the binary log and is now sending it to the slave.
A very brief state that occurs as the thread is stopping.