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

The following will create a simple stored procedure that uses a cursor to kill all processes one by one except for the process currently being used:

DROP PROCEDURE IF EXISTS kill_other_processes;

DELIMITER $$

CREATE PROCEDURE kill_other_processes()
BEGIN
  DECLARE finished INT DEFAULT 0;
  DECLARE proc_id INT;
  DECLARE proc_id_cursor CURSOR FOR SELECT id FROM information_schema.processlist;
  DECLARE CONTINUE HANDLER FOR NOT FOUND SET finished = 1;

  OPEN proc_id_cursor;
  proc_id_cursor_loop: LOOP
    FETCH proc_id_cursor INTO proc_id;

    IF finished = 1 THEN 
      LEAVE proc_id_cursor_loop;
    END IF;

    IF proc_id <> CONNECTION_ID() THEN
      KILL proc_id;
    END IF;

  END LOOP proc_id_cursor_loop;
  CLOSE proc_id_cursor;
END$$

DELIMITER ;

It can be run with SELECTs to show the processes before and after as follows:

SELECT * FROM information_schema.processlist;
CALL kill_other_processes();
SELECT * FROM information_schema.processlist;