Re: Handling Circular Wait / Deadlocks

Hi!

On Jul 20, Adam Retter wrote:
> Hi Chaps,
>
> I am one of the developers on the eXist Open Source Native XML Database.
> At the moment we are having some trouble with Circular Wait conditions,
> which are described well in the diagram at the top of this page -
> http://blogs.msdn.com/bartd/archive/2006/09/25/deadlock-troubleshooting-part-3.aspx
>
> I was wondering how Circular Wait conditions are resolved in MySQL?

It depends.

In MySQL itself (that is, on the upper layer, above storage engines), there's no such a problem - it is deadlock-free. All locks are taken in the beginning of the statement, always in the same order - so no deadlock can possibly occur.

Storage engines may have their own locking policies, and if they allow deadlocks they have some means to resolve them. For example - loop detection in the wait-for graphs, or simply timeouts.  

Regards / Mit vielen Grüssen,
Sergei

-- 
   __  ___     ___ ____  __
  /  |/  /_ __/ __/ __ \/ /   Sergei Golubchik 
 / /|_/ / // /\ \/ /_/ / /__  Principal Software Developer
/_/  /_/\_, /___/\___\_\___/  MySQL GmbH, Radlkoferstr. 2, D-81373 München
       <___/                  Geschäftsführer: Kaj Arnö - HRB München 162140

-- 
MySQL Internals Mailing List
For list archives: 
http://lists.mysql.com/internals
To unsubscribe:    
http://lists.mysql.com/internals?unsub=lists@pantek.com