SET GLOBAL query_cache_size=1355776;
flush query cache;
flush query cache;
reset query cache;
flush status;
SET DEBUG_SYNC='after_query_cache_mutex SIGNAL mutex_locked WAIT_FOR unlock_mutex';
SELECT "mutex_locked_query" as action;
SET DEBUG_SYNC='now WAIT_FOR mutex_locked';
SET DEBUG_SYNC='before_query_cache_mutex SIGNAL try_lock_mutex';
SELECT "try_lock_mutex_query" as action;
SET DEBUG_SYNC='now WAIT_FOR try_lock_mutex';
SELECT SQL_NO_CACHE state FROM INFORMATION_SCHEMA.PROCESSLIST WHERE info='SELECT "try_lock_mutex_query" as action';
state
Waiting on query cache mutex
SET DEBUG_SYNC='now SIGNAL unlock_mutex';
action
mutex_locked_query
action
try_lock_mutex_query
SET GLOBAL query_cache_size=0;
