The function trx_purge_stop() was calling os_event_reset(purge_sys->event) before calling rw_lock_x_lock(&purge_sys->latch). The os_event_set() call in srv_purge_coordinator_suspend() is protected by that X-latch. It would seem a good idea to consistently protect both os_event_set() and os_event_reset() calls with a common mutex or rw-lock in those cases where os_event_set() and os_event_reset() are used like condition variables, tied to changes of shared state. For each os_event_t, we try to document the mutex or rw-lock that is being used. For some events, frequent calls to os_event_set() seem to try to avoid hangs. Some events are never waited for infinitely, only timed waits, and os_event_set() is used for early termination of these waits. os_aio_simulated_put_read_threads_to_sleep(): Define as a null macro on other systems than Windows. TODO: remove this altogether and disable innodb_use_native_aio on Windows. os_aio_segment_wait_events[]: Initialize only if innodb_use_native_aio=0.