Here is the solution:
show full processlist;
to get the process id with status and query itself which causes the database hanging;KILL <pid>;
to kill that process.Sometimes it is not enough to kill each process manually. So, for that we've to go with some trick:
Select concat('KILL ',id,';') from information_schema.processlist where user='user';
to print all processes with KILL
command;|
sign, copy and paste all again into the query console. HIT ENTER. BooM it's done.