Hi, Roberto! On Oct 13, Roberto Spadim wrote: > hi guys, i'm reading https://github.com/MariaDB/server/blob/10.1/sql/mdl.h > i'm with a doubt... today we have the metadata lock plugin to check what > mdl we have... > my doubt is, how to expose how many threads are sharing the mdl key, and > how many threads are waiting the mdl key, should it be possible or only one > threrad could use one mdl?
MDL_key is not a lock, it's just an object key - it specifies what object is locked (or a lock is requested on). Many threads can wait for the same object, of course. Threads do not share the logical lock, if two threads got a shared lock on some object - every thread got its own shared lock, not two threads got the same lock. Logically. But in the code all these shared locks are represented by one MDL_ticket object, not many. Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
