Sorry, *open_files_limit... 2010/2/1 Wagner Bianchi <wagnerbianch...@gmail.com>
> Is FD_SETSIZE regards to an open_file_limit? > > WB > > 2010/2/1 Cui Shijun <rancp...@gmail.com> > > Got your idea. >> Thank you very much. Now I know how table cache works :-) >> >> For the bug, yes, it's related to the value of FD_SETSIZE, which is >> limited to 1024 at my RedHat box. >> Maybe I should update it to a suitable value. >> >> 2010/2/2 Johan De Meersman <vegiv...@tuxera.be>: >> > >> > On Mon, Feb 1, 2010 at 4:51 PM, Cui Shijun <rancp...@gmail.com> wrote: >> >> >> >> I'm also confused by the difference & relationship between "open >> >> table" and "open file descriptor" by the table cache. >> > >> > "open table" is a MySQL concept. "Open file descriptor" is an OS >> concept. A >> > single table (MyISAM) consists of three files: the .frm (description), >> the >> > .MYD (data) and the .MYI (indices). Thus, a single open table can >> correspond >> > to multiple open files. Additionally, temp tables, sortfiles and whatnot >> > also consume file descriptors. >> > >> >> >> >> As far as I understand, when a thread ask the global cache for a >> table: >> >> * if the table is opened before and currently not used by other >> >> thread, the request thread will get this table >> > >> > "and *there is a cache entry that* is currently not used*" - multiple >> > entries can exist for the same table. >> > >> >> >> >> * if no table in table cache is available( currently used by other >> >> thread, or not opened before ), the request thread will open this >> >> table >> > >> > The thread will get a new cache object that opens that table, yes. >> > >> >> >> >> Once open a table, mysql *might?( I'm not sure )* open a file >> >> descriptor corresponding to the data file of the table. In that case, >> >> when the number of table opened simultaneously goes too big, mysql >> >> will use too much file descriptors and then hit the bug 48929. >> >> >> >> Your experience( "I've had one occurrence where it grew to 26.000 >> >> open tables" ) seems to show there must be something wrong with my >> >> understanding, Hmm... :-( >> > >> > I just skimmed over it, but the bug seem related specifically to InnoDB, >> and >> > to a highly specific file descriptor number being equal to some form of >> > hardcoded limit - maybe different OSes or linux distro's have different >> > values for said limit, or maybe it only occurs under specific >> conditions. >> > >> > >> > >> > -- >> > Bier met grenadyn >> > Is als mosterd by den wyn >> > Sy die't drinkt, is eene kwezel >> > Hy die't drinkt, is ras een ezel >> > >> >> -- >> MySQL General Mailing List >> For list archives: http://lists.mysql.com/mysql >> To unsubscribe: >> http://lists.mysql.com/mysql?unsub=wagnerbianch...@gmail.com >> > -- Wagner Bianchi - Web System Developer and Database Administrator Phone: (31) 8654-9510 / 3272-0226 E-mail: wagnerbianch...@gmail.com Lattes: http://lattes.cnpq.br/2041067758113940 Twitter: http://twitter.com/wagnerbianchi Skype: infodbacet
