InnoDB Mutexes are synchronization objects used by the InnoDB storage engine to ensure that different threads can access shared resources safely. Mutex waits can be a bottleneck for performance in MySQL 8, as they can cause contention and block other threads from accessing the database. The Performance Schema in MySQL 8 provides a way to monitor InnoDB Mutex waits and identify potential performance issues.
Here are the steps to monitor InnoDB Mutex waits using Performance Schema:
- Configure Performance Schema: You need to configure the Performance Schema to instrument InnoDB Mutex waits by setting the performance_schema_instrument system variable to “wait/lock/mutex/innodb”.
- Query the Performance Schema tables: You can query the performance_schema.mutex_instances and performance_schema.mutex_waits tables to monitor InnoDB Mutex waits. The performance_schema.mutex_instances table contains information about each InnoDB Mutex, such as its name and address, while the performance_schema.mutex_waits table contains information about threads that are waiting for a Mutex to be released.
- Analyze the data: You can use the information from the performance_schema.mutex_instances and performance_schema.mutex_waits tables to identify InnoDB Mutexes that are experiencing high contention and to optimize your database configuration to reduce Mutex waits.
Here is an example query that you can use to monitor InnoDB Mutex waits:
INNER JOIN performance_schema.mutex_waits ON
performance_schema.mutex_instances.MUTEX_ID = performance_schema.mutex_waits.MUTEX_ID
performance_schema.mutex_instances.NAME LIKE 'InnoDB%'
This query retrieves data about InnoDB Mutex waits, including the number of times a Mutex was waited on, the minimum, average, and maximum wait times, and the name of the Mutex. By analyzing this data, you can identify potential performance bottlenecks and optimize your MySQL configuration to improve performance.