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GDB MySQL参数

苏普

2010-10

Open-files-limit

起源> Can't open file: '.\test\mytable.frm' (errno: 24)shell> perror 24OS error code 24: Too many open files

尝试修改open_files_limit

Changes the number of file descriptors available to mysqld. You should try increasing the value of this option if mysqld gives you the error Too many open files. mysqld uses the option value to reserve descriptors with setrlimit(). If the requested number of file descriptors cannot be allocated, mysqld writes a warning to the error log.

open_files_limit in my.cnf

• 配置 open_files_limit = 10000

global variables like "%open_files_limit%";+------------------+-------+| open_files_limit | 1024 |+------------------+-------+

• 配置 open_files_limit = 30000

global variables like "%open_files_limit%";+------------------+-------+| open_files_limit | 1024 |+------------------+-------+

参数设置始终无效

Why?

• 开启了一个痛苦代码追踪过程

gdb: watch

gdb mysqld(gdb) watch open_files_limit(gdb) r

Old value = 0New value = 20000

Old value = 20000New value = 1024init_common_variables (...) at mysqld.cc:3355

Sql/mysqld.cc:3355

max_open_files= max(max(wanted_files, max_connections*5), open_files_limit);3322 files= my_set_max_open_files(max_open_files);

gdb mysqld(gdb) b mysqld.cc:3322(gdb) r(gdb) n

mysys/my_file.c

uint my_set_max_open_files(uint files){... files= set_max_open_files(min(files, OS_FILE_LIMIT));

mysys/my_file.c

static uint set_max_open_files(uint max_file_limit){... if (rlimit.rlim_cur >= max_file_limit) DBUG_RETURN(rlimit.rlim_cur); rlimit.rlim_cur= rlimit.rlim_max= max_file_limit; if (setrlimit(RLIMIT_NOFILE, &rlimit))

}

Linux && setrlimit

• man setrlimit– set resource limits

Almost Done

• mysqld_safe

if test -w / -o "$USER" = "root"then ...... if test -n "$open_files" then ulimit -n $open_files append_arg_to_args "--open-files-limit=$open_files" fifi

Simple? or not？• That’s all

• Who’s next

Good Luck

Q & A