MySQL 5.6 C API Developer Guide
MYSQL_RES * mysql_list_processes(MYSQL *mysql)
Returns a result set describing the current server threads.
This is the same kind of information as that reported by
mysqladmin processlist or a
SHOW PROCESSLIST query.
You must free the result set with
mysql_free_result().
Commands were executed in an improper order.
The MySQL server has gone away.
The connection to the server was lost during the query.
An unknown error occurred.