On Thursday 07 March 2002 12:42 am, Jeremy Zawodny wrote: > My 4.0.2 slave has run through about 14 million queries and it's going > well.
Good news > > Do you have any feel for how much slower a debugging version of MySQL > is compared to a normal version? ?I ask because my replication > heartbeat monitor has noticed this particular slave falling behind on > replication a fair amount. ?It usually doesn't get too far behind, but > it's certainly farther behind that it's neighbor--which has a slower > CPU. Depends on the queries. I would say it could be from 3 to 10 times slower. To know for sure, use BUILD/compile-pentium instead of BUILD/compile-pentium-debug. This will compile a perfectly optimal binary. > > And could that fact have anything to do with SHOW SLAVE STATUS being > slow sometimes? I've figured out what's up with this one, I think. SHOW SLAVE STATUS needs to acquire a simultaneous lock on the I/O thread and on the SQL thread, and it might be a while before both of them will surrender that lock if they are busy. I have been rather conservative and very possibly made the critical region wider that what it should be. I think part of the problem is also in the FreeBSD mutex implementation - the current holder of the mutex surrenders it for only a very short time and it is possible that there could be some starvation issues. I woder if FreeBSD has different mutex types - in this case, we want the kind that puts fairness above speed. -- MySQL Development Team For technical support contracts, visit https://order.mysql.com/ __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Sasha Pachev <[EMAIL PROTECTED]> / /|_/ / // /\ \/ /_/ / /__ MySQL AB, http://www.mysql.com/ /_/ /_/\_, /___/\___\_\___/ Provo, Utah, USA <___/ --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
