Oracle 5.0 Reference Manual page 1206

•
OS_waits
work (the mutex was not locked during the spinlock and it was necessary to yield to the operating
system and wait).
•
OS_yields
and yielded to the operating system (on the presumption that permitting other threads to run will free
the mutex so that it can be locked).
•
OS_waits_time
timed_mutexes
disabled, so
From MySQL 5.0.33 on, the statement uses the same output format as that just described, but only
if
UNIV_DEBUG
part of the MySQL source tree). If
InnoDB
following fields. In the latter case (without UNIV_DEBUG), the information on which the statement output
is based is insufficient to distinguish regular mutexes and mutexes that protect rw-locks (which permit
multiple readers or a single writer). Consequently, the output may appear to contain multiple rows for
the same mutex.
•
File
The source file where the mutex is implemented.
•
Line
The line number in the source file where the mutex is created. This may change depending on your
version of MySQL.
•
OS_waits
Same as OS_waits_time.
Information from this statement can be used to diagnose system problems. For example, large values
of
spin_waits
SHOW MUTEX STATUS
deprecated and
similar information but in a somewhat different output format.
MySQL 5.5.
13.7.5.23.
SHOW OPEN TABLES
SHOW OPEN TABLES [{FROM | IN} db_name]
[LIKE 'pattern' | WHERE expr]
SHOW OPEN TABLES
Section 8.8.3, "How MySQL Opens and Closes
using more general conditions, as discussed in
The and
FROM
present, indicates which table names to match. The
to those present in the
SHOW OPEN TABLES
•
Database
The database containing the table.
•
Table
indicates the number of operating system waits. This occurs when the spinlock did not
indicates the number of times that a thread trying to lock a mutex gave up its timeslice
indicates the amount of time (in ms) spent in operating system waits, if the
[501] system variable is 1 (ON). If
is 0.
OS_waits_time
was defined at MySQL compilation time (for example, in
and
spin_rounds
was added in MySQL 5.0.3. In MySQL 5.1,
SHOW ENGINE INNODB MUTEX
Syntax
lists the non-TEMPORARY
[896] clauses may be used as of MySQL 5.0.12. The
LIKE
database.
db_name
returns the following columns:
Syntax
SHOW
timed_mutexes
[501]
timed_mutexes
was not defined, the statement displays the
UNIV_DEBUG
may indicate scalability problems.
should be used instead. The latter statement displays
tables that are currently open in the table cache. See
Tables". The
Section 19.18, "Extensions to
clause, if present, restricts the tables shown
FROM
1186
[501] is 0 (OFF), timing is
is off by default.
include/univ.i
SHOW MUTEX STATUS
SHOW MUTEX STATUS
clause can be given to select rows
WHERE
SHOW
[896]
LIKE
in the
is
is removed in
Statements".
clause, if