I ran a SHOW PROCESSLIST while it was hanging and it does show a sleep being ran:
mysql> show processlist\g
+-----+-----------+----------------+---------------+---------+------+-
+------+---
---------------+
| Id | User | Host | db | Command | Time |
+State | In
fo |
+-----+-----------+----------------+---------------+---------+------+-
+------+---
---------------+
| 84 | root | localhost:1332 | rate_calc | Sleep | 1 |
+ | NU
LL |
| 92 | WebClient | localhost:1346 | sch_oxitest08 | Sleep | 957 |
+ | NU
LL |
| 100 | root | localhost:1356 | rate_calc | Query | 0 |
+NULL | sh
ow processlist |
| 106 | root | localhost:1364 | rate_calc | Sleep | 18 |
+ | NU
LL |
+-----+-----------+----------------+---------------+---------+------+-
+------+---
---------------+
4 rows in set (0.00 sec)