[MDEV-24789] Performance regression after MDEV-24671 - Jira

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The fix of ~~MDEV-24671~~ introduced a serious performance regression that is observable at 32 concurrent connections.

My current hypothesis based on some initial investigation is that the changed sizeof(trx->lock) caused an increase of cache misses.

causes

MDEV-25016 Race condition between lock_sys_t::cancel() and page split or merge

MDEV-25371 Potential hang in wsrep_is_BF_lock_timeout()

MDEV-26883 InnoDB hang due to table lock conflict

is caused by

MDEV-24671 Assertion failure in lock_wait_table_reserve_slot()

relates to

MDEV-25016 Race condition between lock_sys_t::cancel() and page split or merge