MySQL: many Sleep processes

I've queried SHOW processlist as root after a server restert, and got a long list of Sleep threads:

```
+-----+-------------+-----------------+---------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+-----+-------------+-----------------+---------+---------+------+-------+------------------+
| 217 | root | localhost | masters | Sleep | 371 | | NULL |
| 251 | mastersuser | localhost:50883 | masters | Sleep | 297 | | NULL |
| 252 | mastersuser | localhost:50884 | masters | Sleep | 297 | | NULL |
| 253 | mastersuser | localhost:50885 | masters | Sleep | 297 | | NULL |
| 254 | mastersuser | localhost:50891 | masters | Sleep | 296 | | NULL |
| 261 | mastersuser | localhost:50897 | masters | Sleep | 281 | | NULL |
| 260 | mastersuser | localhost:50896 | masters | Sleep | 281 | | NULL |
| 262 | mastersuser | localhost:50899 | masters | Sleep | 281 | | NULL |
| 263 | mastersuser | localhost:50900 | masters | Sleep | 280 | | NULL |
| 272 | mastersuser | localhost:50908 | masters | Sleep | 263 | | NULL |
| 273 | mastersuser | localhost:50909 | masters | Sleep | 263 | | NULL |
| 274 | mastersuser | localhost:50911 | masters | Sleep | 263 | | NULL |
| 275 | mastersuser | localhost:50912 | masters | Sleep | 263 | | NULL |
| 287 | mastersuser | localhost:52434 | masters | Sleep | 242 | | NULL |
| 288 | mastersuser | localhost:52435 | masters | Sleep | 242 | | NULL |
| 289 | mastersuser | localhost:52436 | masters | Sleep | 242 | | NULL |
| 290 | mastersuser | localhost:52437 | masters | Sleep | 242 | | NULL |
| 296 | mas

To me, it seems like an application connecting using the 'mastersuser' account is not properly closing connections, so yes I'd say it's a problem. They likely disappear after reaching the wait_timeout or interactive_timeout setting.

StackExchange Database Administrators Q#28384, answer score: 4