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From:Michael Widenius Date:March 4 2000 8:24pm
Subject:Re: Definate Race condition in MySQL
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>>>>> "Joe" == Joe Kislo <kislo@stripped> writes:

>> Any change that you can try and test 3.23.12 with this when it comes
>> ut (hopefully within 48 hours)?  We did a small redesign of the DROP /
>> LOCK code in 3.23 and it should be much better than the old one.
>> 
>> Regards,
>> Monty

Joe> 	Doah.  That didn't take long.  Here's the processlist from my linux box
Joe> running 3.22.32-log:

Joe> | 30 | TT_fcgi   | localhost | TT_fcgi   | Query   | 211  | Waiting on
Joe> cond   | DROP table
Joe> Event;                                                                            
>       
Joe> |
Joe> | 35 | TT_fcgi   | localhost | TT_fcgi   | Query   | 211  | Waiting for
Joe> table | INSERT into Event (eventAction, rawTimeCreated, courseID,
Joe> sectionID, eventCode, rawTimeUpdated, even |
Joe> | 38 | TT_fcgi   | localhost | TT_fcgi   | Query   | 211  |
Joe> Locked            | LOCK TABLES Event_CLASS WRITE, Event
Joe> WRITE;                                                          |
Joe> | 39 | TT_fcgi   | localhost | TT_fcgi   | Query   | 200  | Waiting for
Joe> table | show columns from
Joe> Event;                                                                           
> 
Joe> |

Joe> I'll fetch the 3.23 build and see if I can get it to do the same.  LOCK
Joe> TABLES is a ALL-OR-WAIT mechinism right.. It's not like I swiped one
Joe> lock, and is waiting on the other?

No, it's not a ALL-OR-WAIT;  It gets one lock at the time in a
predeterminate order (see last email) that ensures that the locking is
dead lock free.   (The problem is that DROP TABLE will in this case
defeat the normal locking mechanism)

Joe>  I am locking two tables at the same
Joe> time, and dropping one of them.  Does it release BOTH locks or just
Joe> one?  Perhaps a moot question since it seems like from the above
Joe> processlist the DROP table is -not- returning.  

Regards,
Monty
Thread
Definate Race condition in MySQLJoe Kislo2 Mar
  • Re: Definate Race condition in MySQLsasha3 Mar
  • Definate Race condition in MySQLMichael Widenius3 Mar
  • Re: Definate Race condition in MySQLJoe Kislo3 Mar
    • Re: Definate Race condition in MySQLMichael Widenius4 Mar
  • Re: Definate Race condition in MySQLJoe Kislo3 Mar
    • Re: Definate Race condition in MySQLMichael Widenius4 Mar
  • Re: Definate Race condition in MySQLJoe Kislo3 Mar
    • Re: Definate Race condition in MySQLMichael Widenius4 Mar