The MySQL slow query log often shows a bunch of following entries in sequence.

SET timestamp=1268999330;
commit;
# User@Host: username[username] @ localhost []
# Query_time: 4.172700  Lock_time: 0.000000 Rows_sent: 0  Rows_examined: 0
SET timestamp=1268999330;
commit;
# User@Host: username[username] @ localhost []
# Query_time: 3.628924  Lock_time: 0.000000 Rows_sent: 0  Rows_examined: 0
SET timestamp=1268999330;
commit;
# User@Host: username[username] @ localhost []
# Query_time: 3.116018  Lock_time: 0.000000 Rows_sent: 0  Rows_examined: 0
...

Usually 6-7 "commit" queries in sequence. Anyone what they are and what's the preceding query of each of them?

Thanks in advance.