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Martin Hope
Xenos
Asked: 2020-02-19 07:50:58 +0800 CST
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MySQL 可以运行的计划事件的“实例”数量是否有限制？我已经设置好了：

CREATE TABLE IF NOT EXISTS t (c1 INT UNSIGNED NOT NULL) ENGINE=INNODB;

SELECT * FROM t;

DELIMITER $$

DROP EVENT IF EXISTS e_second;
CREATE EVENT e_second ON SCHEDULE EVERY 1 SECOND
DO BEGIN
    INSERT INTO t (c1) VALUES (UNIX_TIMESTAMP());
    SELECT SLEEP(1000);
    INSERT INTO t (c1) VALUES (UNIX_TIMESTAMP());
END$$

DELIMITER ;

SELECT * FROM t;

SHOW PROCESSLIST;

SHOW VARIABLES LIKE '%connect%';

这会创建一个每秒启动的哑事件，运行时间为 1000 秒。在我的查询日志中，我确实有：

2020-02-18T15:47:00.289050Z      1016 Query     INSERT INTO t (c1) VALUES (UNIX_TIMESTAMP())
2020-02-18T15:47:00.430801Z      1216 Query     INSERT INTO t (c1) VALUES (UNIX_TIMESTAMP())
2020-02-18T15:47:00.430950Z      1216 Query     SELECT SLEEP(200)
2020-02-18T15:47:01.290518Z      1017 Query     INSERT INTO t (c1) VALUES (UNIX_TIMESTAMP())
2020-02-18T15:47:01.430943Z      1217 Query     INSERT INTO t (c1) VALUES (UNIX_TIMESTAMP())
...

所以事件每秒运行一次，并挂起（故意）。现在，进程列表显示（过了一会儿）：

"559"   "root-heidisql" "127.0.0.1" "test_sql"  "Connect"   "702"   "User sleep"    "SELECT SLEEP(1000)"
"560"   "root-heidisql" "127.0.0.1" "test_sql"  "Connect"   "701"   "User sleep"    "SELECT SLEEP(1000)"
"561"   "root-heidisql" "127.0.0.1" "test_sql"  "Connect"   "700"   "User sleep"    "SELECT SLEEP(1000)"
"562"   "root-heidisql" "127.0.0.1" "test_sql"  "Connect"   "699"   "User sleep"    "SELECT SLEEP(1000)"
"563"   "root-heidisql" "127.0.0.1" "test_sql"  "Connect"   "698"   "User sleep"    "SELECT SLEEP(1000)"
...

所以我现在在这个进程列表中有大约 528 行。但是，我的连接限制151如显示变量所示：

"max_connections"   "151"

很明显，正在运行的事件不是连接限制的一部分。那么，极限是多少？有吗？

在我看来，在某些时候，一些 mysql 队列/列表/任何东西都会充满未决事件......这个案例是否记录在某个地方？

mysql mysql-event