mysqladmin在SuSE linux系统中--sleep参数使用不准确问题
浏览数：22 /
时间：2015年06月12日
我们都知道，在MySQL中，可以使用mysqladmin命令的extended-status选项来查看MySQL的运行状态，比如获取我们常常关注的几个值：
# mysqladmin -uroot -proot ext |grep "Questions\|Queries\|Innodb_rows\|Com_select \|Com_insert \|Com_update \|Com_delete " | Com_delete | 26750 | | Com_insert | 347420 | | Com_select | 1341126 | | Com_update | 454425 | | Innodb_rows_deleted | 26590 | | Innodb_rows_inserted | 347416 | | Innodb_rows_read | 2964050 | | Innodb_rows_updated | 695605 | | Queries | 2304578 | | Questions | 2259777 |但这样得到的数值都累计的，如果想了解当前的状态，则需要进行一次差值计算，而庆幸的是，这个客户端工具提供了两个参数，这样就能实时的得到当前数据库的相关参数值：
-i, --sleep=# Execute commands again and again with a sleep between，单位是秒
-r, --relative Show difference between current and previous values when
used with -i. Currently works only with extended-status.
# mysqladmin -uroot -proot ext -i 1 -r |grep "Questions\|Queries\|Innodb_rows\|Com_select \|Com_insert \|Com_update \|Com_delete " | Com_delete | 26750 | | Com_insert | 347420 | | Com_select | 1341129 | | Com_update | 454425 | | Innodb_rows_deleted | 26590 | | Innodb_rows_inserted | 347416 | | Innodb_rows_read | 2964050 | | Innodb_rows_updated | 695605 | | Queries | 2304592 | | Questions | 2259791 |这样就得到了MySQL当前数据库每秒中对应值，很直观，这个命令在RHEL 6.4 x86_64系统上可以正常使用。但在SuSE linux 11sp1 x86_64系统中，却是不准确的，即使用-i（或--sleep=）指定刷新的秒数，但事实并非如此。
在测试中，经常是指定了--sleep=1，但显示结果却是大概1分多钟刷新一次，非常奇怪。但在使用strace跟踪发现了原因：
# strace mysqladmin -uroot -proot ext -i 1 -r |grep "Questions\|Queries\|Innodb_rows\|Com_select \|Com_insert \|Com_update \|Com_delete "
execve("/usr/bin/mysqladmin", ["mysqladmin", "-uroot", "-proot", "ext", "-i", "1", "-r"], [/* 59 vars */]) = 0
brk(0) = 0x62a000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f0c036fe000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/usr/lib64/mysql/tls/x86_64/libmysqlclient.so.15", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/mysql/tls/x86_64", 0x7fffbb00c0f0) = -1 ENOENT (No such file or directory)
open("/usr/lib64/mysql/tls/libmysqlclient.so.15", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/mysql/tls", 0x7fffbb00c0f0) = -1 ENOENT (No such file or directory)
open("/usr/lib64/mysql/x86_64/libmysqlclient.so.15", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/mysql/x86_64", 0x7fffbb00c0f0) = -1 ENOENT (No such file or directory)
open("/usr/lib64/mysql/libmysqlclient.so.15", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\300\262\1\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1420448, ...}) = 0
mmap(NULL, 3521032, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f0c03185000
fadvise64(3, 0, 3521032, POSIX_FADV_WILLNEED) = 0
mprotect(0x7f0c032ac000, 2093056, PROT_NONE) = 0
mmap(0x7f0c034ab000, 217088, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x126000) = 0x7f0c034ab000
mmap(0x7f0c034e0000, 2568, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f0c034e0000
close(3) = 0
…… <==== 省略若干 ====>
write(1, "+-------------------------------"..., 4096) = 4096
write(1, " | 0 "..., 4096) = 4096
write(1, " |\n| Com_truncate "..., 4096) = 4096
write(1, "ze | 163"..., 4096) = 4096
rt_sigprocmask(SIG_BLOCK, [CHLD], [], 8) = 0
rt_sigaction(SIGCHLD, NULL, {SIG_DFL, [], 0}, 8) = 0
rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0
<span style="color:#ff0000;">nanosleep({83, 0}</span>,| Com_delete | 26750 |
| Com_insert | 347420 |
| Com_select | 1341136 |
| Com_update | 454425 |
| Innodb_rows_deleted | 26590 |
| Innodb_rows_inserted | 347416 |
| Innodb_rows_read | 2964050 |
| Innodb_rows_updated | 695605 |
| Queries | 2304622 |
| Questions | 2259821 |问题就在即使指定的是1秒刷新，但系统调用时却是83s刷新一次：nanosleep({83, 0}很可惜，这个功能不在这个系统中使用，更不幸的时，生产环境中的全都SuSE linux 11sp1系统，郁闷......
准备找个机会，向SUSE原厂问一下，到底什么情况的。
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