# The number of wait/synch/mutex/sql/MDL\_ticket\_store::LOCK\_ticket\_store\_ops in mutex\_instances is constantly growing **URL:** \ **Category:** Percona XtraDB Cluster\ **Created:** [October 17, 2025, 9:29am UTC](https://forums.percona.com/t/the-number-of-wait-synch-mutex-sql-mdl-ticket-store-lock-ticket-store-ops-in-mutex-instances-is-constantly-growing/39571 "2025-10-17T09:29:00Z")\ **Posts on this page:** 1\ **Showing post:** 5
**Author:** ![iva3682](https://avatars.discourse-cdn.com/v4/letter/i/4491bb/32.png) [@iva3682](https://forums.percona.com/u/iva3682)\ **Post date:** [November 27, 2025, 6:09am UTC](https://forums.percona.com/t/the-number-of-wait-synch-mutex-sql-mdl-ticket-store-lock-ticket-store-ops-in-mutex-instances-is-constantly-growing/39571/5 "2025-11-27T06:09:19Z")
@anil.joshi Sorry for the long response. Yes, the growing number of records in performance\_schema.mutex\_instances leads to serious problems, as each record in the performance\_schema.mutex\_instances table also creates a corresponding record in the performance\_schema.events\_waits\_summary\_global\_by\_event\_name table. With PMM installed and the recommended settings, PMM makes a high-frequency query to the performance\_schema.events\_waits\_summary\_global\_by\_event\_name table, which looks like this: `SELECT` `EVENT_NAME,` `COUNT_STAR,` `SUM_TIMER_WAIT` `FROM` `performance_schema.events_waits_summary_global_by_event_name` The more records there are in the performance\_schema.events\_waits\_summary\_global\_by\_event\_name table, the slower this query runs. Over time, this query itself starts to appear in the slow query log. For now, I’ve found a workaround by adding a setting to mysql.cnf: `performance_schema_max_mutex_instances = 20000` --- _[View the full topic](https://forums.percona.com/t/the-number-of-wait-synch-mutex-sql-mdl-ticket-store-lock-ticket-store-ops-in-mutex-instances-is-constantly-growing/39571)._