=) no problem about disagree, i'm agree now hehe thanks guys! :)
2013/10/29 Sergey Vojtovich <[email protected]> > Hi Kentoku, > > thanks for your contribution and sorry for this long delay. I finally > managed > to go through your code. > > The most important thing I'm worried about is that there is no protection > of ticket lists: lists may be updated while we iterate them and it may > cause > server crash in concurrent environment. From what I can see MDL_context is > mostly supposed to be accessed only by thread which owns this context. As > such > it is not protected by any locks. > > I believe we should use global lists instead, something like: > mysql_mutex_lock(&mdl_locks.m_mutex); > iterate mdl_locks.m_locks (hash of MDL_lock) > { > mysql_prlock_rdlock(&lock->m_rwlock); > iterate lock->m_granted (list of MDL_ticket) > { > // store data > } > mysql_prlock_unlock(&lock->m_rwlock); > } > mysql_mutex_lock(&mdl_locks.m_mutex); > > A few more suggestions in no particular order: > - instead of making m_tickets public I'd suggest to try to make > i_s_metadata_lock_info_fill_table() a friend function > (shouldn't be relevant anymore) > > - why check for thd->killed? > (shouldn't be relevant anymore) > > - metadata_lock_info_lock_mode_length[] includes ending zero, and then > we store e.g. "MDL_SHARED\0" whereas we should store "MDL_SHARED" > > I'd suggest to declare these arrays as following: > static const LEX_STRING metadata_lock_info_lock_mode_str[]= > { > STRING_WITH_LEN("MDL_INTENTION_EXCLUSIVE"), // or C_STRING_WITH_LEN() > ... > }; > > - Roberto suggests to rename ID to THREAD_ID and I agree > - Roberto suggests to add QUERY_ID column and I agree > - Roberto suggests to add LOCK_DURATION column and I agree > - Roberto suggests to use m_namespace_to_wait_state_name instead of > metadata_lock_info_lock_names, but I tend to disagree because the former > says > "Waiting for...". Though I'd suggest to make array of LEX_STRING's to > avoid > calling strdup(). > > - Roberto suggests to replace DB with KEY and NAME with SUB_KEY, but I > tend to > disagree since in most cases it is db and table name. I'd vote for > TABLE_SCHEMA and TABLE_NAME to stay in line with the rest I_S tables. > > Regards, > Sergey > > On Mon, Jul 01, 2013 at 03:46:22AM +0900, kentoku wrote: > > Hi Sergey, > > Sorry. I think this plugin needs more locks "mdl_locks.m_mutex", > > "mdl_locks.m_global_lock" and "mdl_locks.m_commit_lock". Is it right? > Would > > you please teach me how can I use it? > > Thanks, > > Kentoku > > > > > > 2013/7/1 kentoku <[email protected]> > > > > > Hi Sergey, > > > > > > I made new information schema plugin which named "metadata_lock_info" > > > plugin. This plugin makes it possible knowing "who has metadata > locks". In > > > development stage, sometimes DBAs meet metadata locks when using alter > > > table statement. This metadata locks are sometimes caused by GUI > tools. In > > > service stage, sometimes DBAs meet metadata locks when using alter > table > > > statement. This metadata locks are sometimes caused by long batch > > > processing. In many cases, the DBAs need to judge immediately. So I > made it > > > for all DBAs. > > > Would you please review this plugin? > > > lp:~kentokushiba/maria/10.0.3-metadata_lock_info > > > Note: This plugin needs a change of sql/mdl.h > > > > > > Thanks, > > > Kentoku > > > > > _______________________________________________ > Mailing list: https://launchpad.net/~maria-developers > Post to : [email protected] > Unsubscribe : https://launchpad.net/~maria-developers > More help : https://help.launchpad.net/ListHelp > -- Roberto Spadim SPAEmpresarial
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