pmp-check-mysql-deadlocks interval argument accepts fractions of a second but silently performs rounding at 1-minute granularity

[Ryan Lowe]

pmp-check-mysql-deadlocks interval argument accepts fractions of a second but silently performs rounding at 1-minute granularity. For example:

perl ./pmp-check-mysql-deadlocks -i 0.0000001

Executes just fine, but internally INTERVAL subtraction (and rounding) is used, which is only to the nearest minute.

(via line 62)

62 LEVEL=$(mysql_exec "SELECT COUNT(*) FROM ${OPT_TABLE} WHERE ts >= NOW() - INTERVAL ${OPT_INTERVAL} MINUTE")

Here's my example of the one-minute rounding:

mysql> select now(), now() - interval 0.6 minute;
+---------------------+-----------------------------+
| now() | now() - interval 0.6 minute |
+---------------------+-----------------------------+
| 2013-03-13 13:24:27 | 2013-03-13 13:23:27 |
+---------------------+-----------------------------+
1 row in set (0.00 sec)

mysql> select now(), now() - interval 0.5 minute;
+---------------------+-----------------------------+
| now() | now() - interval 0.5 minute |
+---------------------+-----------------------------+
| 2013-03-13 13:24:35 | 2013-03-13 13:23:35 |
+---------------------+-----------------------------+
1 row in set (0.00 sec)

mysql> select now(), now() - interval 0.4 minute;
+---------------------+-----------------------------+
| now() | now() - interval 0.4 minute |
+---------------------+-----------------------------+
| 2013-03-13 13:26:19 | 2013-03-13 13:26:19 |
+---------------------+-----------------------------+
1 row in set (0.00 sec)

Solution:

Either fix it to round to the nearest second (except in 5.6, which can be more granular) or specify this limitation in the documentation.

[Roman Vynar (roman-vynar)]

Will be rounding to the nearest second.

- LEVEL=$(mysql_exec "SELECT COUNT(*) FROM ${OPT_TABLE} WHERE ts >= NOW() - INTERVAL ${OPT_INTERVAL} MINUTE")
+ LEVEL=$(mysql_exec "SELECT COUNT(*) FROM ${OPT_TABLE} WHERE ts >= NOW() - INTERVAL ${OPT_INTERVAL}*60 SECOND")