MyISAM storage engine supports concurrent inserts. If there are multiple INSERT statements, they are queued and performed in sequence, concurrently with the SELECT statements.

The concurrent_insert system variable can be set to modify the concurrent-insert processing. This variable is set to 1 by default. To disable concurrent insert just set concurrent_insert variable to 0. If the variable is set to 2, concurrent inserts at the end of the table are allowed even for tables that have deleted rows. See also the description of the concurrent_insert system variable.