Comments on: How innodb_open_files affects performance

By: DaveJ

DaveJ — Wed, 14 Apr 2010 14:11:23 +0000

I posted a comment on http://www.mysqlperformanceblog.com/2009/11/16/table_cache-negative-scalability/ asking about open_file_limit.

One thing I see that is not talked about is how the os ulimit of “open files”, mysql setting “open_file_limit” affects the OS/MySQL and I believe is non-biased to MyISAM and InnoDB table types.

If the max open_file_limit is 65535, does this mean a linux 64bit server could never have more than that opened at a given time?

How would you work around this and why wouldn’t MySQL use LRU algorithm to close OS open’ed files if the max is hit and avoid errno 24 (too many open files)?

Thanks.

By: tiger

tiger — Thu, 03 Dec 2009 08:25:00 +0000

Its wonderful and absolute

By: peter

peter — Thu, 19 Nov 2009 16:34:47 +0000

Ryan,

See the previous post on this matter. If you’re running into hundreds of thousands or more tables large table cache may be actually hurting you.

We have not investigated it but I trust there is something relatively simple which gets proportionally slower.

By: Ryan H

Ryan H — Thu, 19 Nov 2009 05:07:40 +0000

We have our table_cache set to 16384 on our server and we are running into performance issue with this setting especially on QA servers where we recreate hundreds of databases daily (with 300+ tables each) then process to recreate them get’s worse and worse over time with the table cache seeming to be the primary culprit. Is this listed as a bug anywhere currently?

-Ryan