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https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-metric-sysschema-tablemetadatalockwaiters-category.html
Lists the Sys Schema Table Metadata Lock Waits metrics and provides a brief description of each. Table 6.41 Sys Schema Table Metadata Lock Waits Metrics NameDescriptionBlocking Account The account of the session that is blocking the current ...The ...
https://dev.mysql.com/doc/refman/8.4/en/sys-innodb-lock-waits.html
These views summarize the InnoDB locks that transactions are waiting for. The innodb_lock_waits and x$innodb_lock_waits views have these columns: wait_started The time at which the lock wait started. wait_age How long the lock has been waited for, ...waiting_trx_age How long the waiting transaction has been waiting, as a TIME ...
https://dev.mysql.com/doc/mysql-em-plugin/en/myoem-metric-sysschema-innodbrowlockwaiters-category.html
Lists the Sys Schema InnoDB Row Lock Waits metrics and provides a brief description of each.
https://dev.mysql.com/doc/refman/8.4/en/mysql-cluster-ndbinfo-locks-per-fragment.html
The locks_per_fragment table provides information about counts of lock claim requests, and the outcomes of these requests on a per-fragment basis, serving as a companion table to operations_per_fragment and memory_per_fragment. This table also ...
https://dev.mysql.com/doc/refman/8.4/en/sys-schema-table-lock-waits.html
These views display which sessions are blocked waiting on metadata locks, and what is blocking them. For additional information, see the description of the Performance Schema metadata_locks table at Section 29.12.13.3, “The metadata_locks ...
https://dev.mysql.com/doc/internals/en/innodb-mutex-rwlock-implementation.html
InnoDB synchronizes these accesses with its own implementation of mutexes and read/write locks. Historically, InnoDB protected the internal state of a read/write lock with an InnoDB mutex, and the internal state of an InnoDB mutex was protected by a ... In MySQL and InnoDB, multiple threads of execution access shared data ...
https://dev.mysql.com/doc/internals/en/starting-transaction-from-external-lock-method.html
MySQL calls [custom-engine.html#custom-engine-api-reference-external_lock handler::external_lock()] for every table it is going to use at the beginning of every statement. Note that because of pre-locking, all tables that can be potentially used ...
https://dev.mysql.com/doc/internals/en/external-lock.html
Synopsis virtual int external_lock ( thd, lock_type); THD * thd ; int lock_type ; Description This is the external_lock method. The locking methods for mysql section in lock.cc has additional comments on this topic that may be useful to read. If you ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-information-schema-internal-data.html
The data exposed by the transaction and locking tables (INFORMATION_SCHEMA INNODB_TRX table, Performance Schema data_locks and data_lock_waits tables) represents a glimpse into fast-changing data. The underlying data is internal system-managed ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-performance-spin_lock_polling.html
InnoDB mutexes and rw-locks are typically reserved for short intervals. On a multi-core system, it can be more efficient for a thread to continuously check if it can acquire a mutex or rw-lock for a period of time before it sleeps. If the mutex or ...InnoDB minimizes this issue by forcing a random delay between polls to desynchronize polling ...