How do I kill all the processes in Mysql “show processlist”?

Question

Because I see a lot of processes there, and the \"time\" column shows big values for all of them.

Answer 1

Here is a solution that you can execute without relying on the operating system:

STEP 1: Create a stored procedure.

DROP PROCEDURE IF EXISTS  kill_user_processes$$ 

CREATE PROCEDURE `kill_user_processes`(
  IN user_to_kill VARCHAR(255)
)
READS SQL DATA
BEGIN

  DECLARE name_val VARCHAR(255);
  DECLARE no_more_rows BOOLEAN;
  DECLARE loop_cntr INT DEFAULT 0;
  DECLARE num_rows INT DEFAULT 0;

  DECLARE friends_cur CURSOR FOR
    SELECT CONCAT('KILL ',id,';') FROM information_schema.processlist WHERE USER=user_to_kill;

  DECLARE CONTINUE HANDLER FOR NOT FOUND
    SET no_more_rows = TRUE;

  OPEN friends_cur;
  SELECT FOUND_ROWS() INTO num_rows;

  the_loop: LOOP

    FETCH  friends_cur
    INTO   name_val;

    IF no_more_rows THEN
        CLOSE friends_cur;
        LEAVE the_loop;
    END IF;


 SET @s = name_val;
    PREPARE stmt FROM @s;
    EXECUTE stmt;
    DEALLOCATE PREPARE stmt;

    SELECT name_val;

    SET loop_cntr = loop_cntr + 1;

  END LOOP the_loop;

  SELECT num_rows, loop_cntr;

END $$
DELIMITER ;

STEP 2: Call the stored procedure giving it the name of a database user whose processes you want to kill. You could rewrite the stored procedure to filter on some other criteria if you like.

CALL kill_user_processes('devdba');