MySQL数据库性能调优

Question

我开发了一个PHP和MySQL Web应用程序。 最近它已显示出放缓的迹象。 我在090516上运行了mysql-tuner，正常运行时间为12天。

服务器规格如下：
- Linux CentOS 6
- 48个处理器
- 64GB RAM

这是从090516到12d正常运行时间的mysql-tuner日志输出：

root@layer1 [~/mysqltuner]# perl mysqltuner.pl --outputfile /~/mysqltuner/result_mysqltuner.txt
String found where operator expected at mysqltuner.pl line 3096, near
        "get_wsrep_option 'gcache.mem_size'" (#1)
    (S syntax) The Perl lexer knows whether to expect a term or an operator.
    If it sees what it knows to be a term when it was expecting to see an
    operator, it gives you this warning.  Usually it indicates that an
    operator or delimiter was omitted, such as a semicolon.

        (Do you need to predeclare get_wsrep_option?)
Use of implicit split to @_ is deprecated at mysqltuner.pl line 3179 (#2)
    (D deprecated, W syntax) It makes a lot of work for the compiler when you
    clobber a subroutine's argument list, so it's better if you assign the results
    of a split() explicitly to an array (or list).

 >>  MySQLTuner 1.6.10 - Major Hayden <major@mhtx.net>
 >>  Bug reports, feature requests, and downloads at http://mysqltuner.com/
 >>  Run with '--help' for additional options and output filtering

[--] Skipped version check for MySQLTuner script
[OK] Currently running supported MySQL version 5.6.31-log
[OK] Operating on 64-bit architecture

-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +ARCHIVE +BLACKHOLE +CSV -FEDERATED +InnoDB +MEMORY +MRG_MYISAM +MyISAM +PERFORMANCE_SCHEMA
[--] Data in MyISAM tables: 913M (Tables: 11)
[--] Data in InnoDB tables: 12M (Tables: 63)
[!!] Total fragmented tables: 11

-------- Security Recommendations ------------------------------------------------------------------
[OK] There are no anonymous accounts for any database users
[OK] All database users have passwords assigned
[!!] User 'munin@localhost' has user name as password.
[--] There are 605 basic passwords in the list.

-------- CVE Security Recommendations --------------------------------------------------------------
[OK] NO SECURITY CVE FOUND FOR YOUR VERSION
Argument "gcache.mem_size" isn't numeric in addition (+) at mysqltuner.pl line
        1965 (#3)
    (W numeric) The indicated string was fed as an argument to an operator
    that expected a numeric value instead.  If you're fortunate the message
    will identify which operator was so unfortunate.

Argument "gcache.mem_size" isn't numeric in addition (+) at mysqltuner.pl line
        1972 (#3)

-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 12d 6h 21m 24s (2 q [0.000 qps], 1M conn, TX: 192B, RX: 240B)
[--] Reads / Writes: 100% / 0%
[--] Binary logging is disabled
[--] Physical Memory     : 62.8G
[--] Max MySQL memory    : 338.9M
[--] Other process memory: 505.0M
[--] Total buffers: 169.0M global + 1.1M per thread (151 max threads)
[--] P_S Max memory usage: 0B
Argument "*main::get_wsrep_option" isn't numeric in numeric ge (>=) at
        mysqltuner.pl line 285 (#3)
Argument "*main::get_wsrep_option" isn't numeric in numeric ge (>=) at
        mysqltuner.pl line 288 (#3)
Argument "*main::get_wsrep_option" isn't numeric in numeric ge (>=) at
        mysqltuner.pl line 291 (#3)
[--] Galera GCache Max memory usage: *main::get_wsrep_optionB
[OK] Maximum reached memory usage: 340.0M (0.53% of installed RAM)
[OK] Maximum possible memory usage: 338.9M (0.53% of installed RAM)
[OK] Overall possible memory usage with other process is compatible with memory available
[OK] Slow queries: 0% (0/2)
[!!] Highest connection usage: 100%  (152/151)
[OK] Aborted connections: 0.00%  (34/1098331)
[OK] Query cache is disabled by default due to mutex contention.
[OK] No Sort requiring temporary tables
[OK] No joins without indexes
[OK] No tmp tables created on disk
[OK] Thread cache hit rate: 98% (17K created / 1M connections)
[OK] Table cache hit rate: 100% (381 open / 0 opened)
[OK] Open file limit used: 2% (228/10K)
[!!] Table locks acquired immediately: 94%

-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is disabled.

-------- Performance schema ------------------------------------------------------------------------
[--] Performance schema is disabled.
[--] Memory used by P_S: 0B

-------- MyISAM Metrics ----------------------------------------------------------------------------
[OK] Key buffer used: 100.0% (8M used / 8M cache)
[!!] Key buffer size / total MyISAM indexes: 8.0M/147.7M
[!!] Read Key buffer hit rate: 87.6% (16M cached / 1M reads)
[!!] Write Key buffer hit rate: 56.8% (1M cached / 777K writes)

-------- AriaDB Metrics ----------------------------------------------------------------------------
[--] AriaDB is disabled.

-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[OK] InnoDB buffer pool / data size: 128.0M/12.1M
[!!] InnoDB buffer pool <= 1G and innodb_buffer_pool_instances(!=1).
[!!] InnoDB Used buffer: 17.82% (1460 used/ 8192 total)
[OK] InnoDB Read buffer efficiency: 100.00% (290756388 hits/ 290757478 total)
[!!] InnoDB Write Log efficiency: 12.12% (3691 hits/ 30446 total)
[OK] InnoDB log waits: 0.00% (0 waits / 34137 writes)

-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.

-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.

-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] This is a standalone server.

-------- Recommendations ---------------------------------------------------------------------------
General recommendations:
    Run OPTIMIZE TABLE to defragment tables for better performance
    Set up a Secure Password for user@host ( SET PASSWORD FOR 'user'@'SpecificDNSorIp' = PASSWORD('secure_password'); )
    Reduce or eliminate persistent connections to reduce connection usage
    Optimize queries and/or use InnoDB to reduce lock wait
Variables to adjust:
    max_connections (> 151)
    wait_timeout (< 28800)
    interactive_timeout (< 28800)
    key_buffer_size (> 147.7M)
    innodb_buffer_pool_instances (=1)

我很少有东西跳出来，但我不是一个经验丰富的MySQL DBA，因此我正在寻求堆栈社区的建议。 请告知我应该在my.cnf中修改哪些设置，如果需要在PHPMYADMIN中对表进行碎片整理，是否需要在非工作时间完成。

我没有注意到我的网络应用程序直到最近才放慢速度，最近我在内核更新后重新启动了服务器。 截至此帖的当前正常运行时间为19小时。

**额外信息：**网络应用程序有一个前端，用户使用移动设备登录，后端有办公室员工管理提交（表格）并将其发送到不同的部门。

如果需要，我可以用munin图表更新。 我知道服务器严重过度配置（这意味着它有更多的内存和处理器，但是我希望在未来有更多的内容）。 我的问题是，我可以简单地调整一些my.cnf设置（如mysqltuner和/或phpmyadmin建议的那样）以提高效率吗？

Answer 1

在接下来的十年中，MySQL不太可能以一种有效使用超过四个处理器的方式进行重构。 因此，您的配置会浪费44个处理器核心。 这似乎太多了。 此外，看起来MySQL使用的内存不到1GiB。

通常，MySQL是内置的，而不是up。 含义：大多数使用数据库镜像扩展基于MySQL的应用程序的人都这样做。 MariaDB的最新版本具有多主镜像方案。

您遇到麻烦的唯一明显区域是连接搅动。 您可能应该编辑my.cnf文件以增加您使用的同时连接数。

您需要调查您的网络应用是否使用连接池。 Web应用程序建立与数据库的连接需要一段时间，如果您为每个Web请求重新建立连接打开操作可能成为瓶颈。 您的统计信息每天24小时，每天12天，每秒显示一个以上的新连接。 除非您的工作量在当天24小时内非常稳定地展开，否则这意味着您的网络应用程序将以非常高的新连接率达到峰值。 这可能是导致经济放缓的原因。

您没有说明您正在使用哪种Web应用程序平台。 大多数平台都有连接池操作。 大多数Web应用程序使用单个集合（或两组）DBMS凭据（用户名）执行所有Web应用程序操作，因此他们可以重用池中的连接。 您的统计信息表明您在数据库中拥有600多个不同的用户。 对于网络应用来说，这是很多。

此外（这是违反直觉的）有时太多的网络应用程序线程可能会损害性能。 有时，用户体验限制线程数更好，让Web服务器排队来自客户端的请求，而不是尝试一次执行太多操作。 现代服务器上的TCP堆栈允许合理深度的SYN请求队列，因此排队不会引人注意。

这是基于您所显示的有限数据的意见：您的瓶颈不是MySQL。