Information Schema INNODB_MUTEXES Table
The INNODB_MUTEXES
table monitors mutex and rw locks waits. It has the following columns:
Column | Description |
---|---|
NAME | Name of the lock, as it appears in the source code. |
CREATE_FILE | File name of the mutex implementation. |
CREATE_LINE | Line number of the mutex implementation. |
OS_WAITS | How many times the mutex occurred. |
The CREATE_FILE
and CREATE_LINE
columns depend on the InnoDB/XtraDB version.
Note that since MariaDB 10.2.2, the table has only been providing information about
rw_lock_t, not any mutexes. From MariaDB 10.2.2 until MariaDB 10.2.32, MariaDB 10.3.23, MariaDB 10.4.13 and MariaDB 10.5.1, the NAME
column was not populated (MDEV-21636).
The SHOW ENGINE INNODB STATUS statement provides similar information.
Examples
SELECT * FROM INNODB_MUTEXES; +------------------------------+---------------------+-------------+----------+ | NAME | CREATE_FILE | CREATE_LINE | OS_WAITS | +------------------------------+---------------------+-------------+----------+ | &dict_sys->mutex | dict0dict.cc | 989 | 2 | | &buf_pool->flush_state_mutex | buf0buf.cc | 1388 | 1 | | &log_sys->checkpoint_lock | log0log.cc | 1014 | 2 | | &block->lock | combined buf0buf.cc | 1120 | 1 | +------------------------------+---------------------+-------------+----------+
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