What could cause all the MySQL connections to sleep?

Question

For some reason,the connections to my local database are put to sleep, even though the database is not actually doing anything:

mysql> SHOW FULL PROCESSLIST;
+-----+------+-----------+-----+---------+------+-------+-----------------------+
| Id  | User | Host      | db  | Command | Time | State | Info                  |
+-----+------+-----------+-----+---------+------+-------+-----------------------+
|  85 | root | localhost | *** | Sleep   |  810 |       | NULL                  |
|  88 | root | localhost | *** | Sleep   |  662 |       | NULL                  |
|  89 | root | localhost | *** | Sleep   |  586 |       | NULL                  |
|  93 | root | localhost | *** | Sleep   |  692 |       | NULL                  |
|  98 | root | localhost | *** | Sleep   |  719 |       | NULL                  |
| 102 | root | localhost | *** | Sleep   |  545 |       | NULL                  |
| 182 | root | localhost | *** | Query   |    0 | init  | SHOW FULL PROCESSLIST |
| 263 | root | localhost | *** | Sleep   |  809 |       | NULL                  |
| 275 | root | localhost | *** | Sleep   |  660 |       | NULL                  |
| 279 | root | localhost | *** | Sleep   |  584 |       | NULL                  |
| 282 | root | localhost | *** | Sleep   |    1 |       | NULL                  |
| 283 | root | localhost | *** | Sleep   |  544 |       | NULL                  |
+-----+------+-----------+-----+---------+------+-------+-----------------------+
12 rows in set (0.00 sec)

No new connections are being made and there's no lock, but somehow the requests are not being processed. Any idea what could be causing this?

Google to the rescue! http://stackoverflow.com/questions/4053744/mysql-show-processlist-lists-many-processes-sleep-and-info-null — Digital Chris, Jan 02 '14 at 19:15
Does this answer your question? [MySql Proccesslist filled with "Sleep" Entries leading to "Too many Connections"?](https://stackoverflow.com/questions/2407732/mysql-proccesslist-filled-with-sleep-entries-leading-to-too-many-connections) — Dr. Gianluigi Zane Zanettini, Sep 02 '22 at 14:08

score 1 · Accepted Answer · answered Jan 02 '14 at 19:47

1

In this context Sleep simply means that the thread is idle. Here's the definition from the manual:

Sleep

The thread is waiting for the client to send a new statement to it.

answered Jan 02 '14 at 19:47

Ike Walker

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score 0 · Answer 2 · answered Sep 03 '21 at 17:08

By default PHP is configured to allow persistent MySQL connections. That's why you're seeing all these sleeping connections, just waiting to be re-used.

Whether you want to use persistent links or not is a different question, but if you want to disable it then you need to make a change to your PHP.ini

mysql.allow_persistent = Off

What could cause all the MySQL connections to sleep?

2 Answers2