Mysql高CPU使用率(100%)

We are facing problem of high cpu usage for mysql process (almost 100%). Here is the information related to server

  1. Server Info: Windows Server 2008 R2 Datacenter Edition Service Pack 1 i586
  2. PHP Running on: Microsoft-IIS/7.5
  3. PHP version: 5.3.28
  4. MySql Server version: 5.5.16 - MySQL Community Server (GPL)

We are also adding code of my.ini file - configuration file of mysql

    # MySQL Server Instance Configuration File
# ----------------------------------------------------------------------
# Generated by the MySQL Server Instance Configuration Wizard
#
#
# Installation Instructions
# ----------------------------------------------------------------------
#
# On Linux you can copy this file to /etc/my.cnf to set global options,
# mysql-data-dir/my.cnf to set server-specific options
# (@localstatedir@ for this installation) or to
# ~/.my.cnf to set user-specific options.
#
# On Windows you should keep this file in the installation directory 
# of your server (e.g. C:\Program Files\MySQL\MySQL Server X.Y). To
# make sure the server reads the config file use the startup option 
# "--defaults-file". 
#
# To run run the server from the command line, execute this in a 
# command line shell, e.g.
# mysqld --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini"
#
# To install the server as a Windows service manually, execute this in a 
# command line shell, e.g.
# mysqld --install MySQLXY --defaults-file="C:\Program Files\MySQL\MySQL Server X.Y\my.ini"
#
# And then execute this in a command line shell to start the server, e.g.
# net start MySQLXY
#
#
# Guildlines for editing this file
# ----------------------------------------------------------------------
#
# In this file, you can use all long options that the program supports.
# If you want to know the options a program supports, start the program
# with the "--help" option.
#
# More detailed information about the individual options can also be
# found in the manual.
#
#
# CLIENT SECTION
# ----------------------------------------------------------------------
#
# The following options will be read by MySQL client applications.
# Note that only client applications shipped by MySQL are guaranteed
# to read this section. If you want your own MySQL client program to
# honor these values, you need to specify it as an option during the
# MySQL client library initialization.
#
[client]

port=3306

[mysql]

default-character-set=utf8


# SERVER SECTION
# ----------------------------------------------------------------------
#
# The following options will be read by the MySQL Server. Make sure that
# you have installed the server correctly (see above) so it reads this 
# file.
#
[mysqld]

# The TCP/IP Port the MySQL Server will listen on
port=3306


#Path to installation directory. All paths are usually resolved relative to this.
basedir="C:/Program Files/MySQL/MySQL Server 5.5/"

#Path to the database root
datadir="C:/ProgramData/MySQL/MySQL Server 5.5/Data/"

# The default character set that will be used when a new schema or table is
# created and no character set is defined
character-set-server=utf8

# The default storage engine that will be used when create new tables when
default-storage-engine=INNODB

# Set the SQL mode to strict
sql-mode="STRICT_TRANS_TABLES,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"

# The maximum amount of concurrent sessions the MySQL server will
# allow. One of these connections will be reserved for a user with
# SUPER privileges to allow the administrator to login even if the
# connection limit has been reached.
max_connections=100

# Query cache is used to cache SELECT results and later return them
# without actual executing the same query once again. Having the query
# cache enabled may result in significant speed improvements, if your
# have a lot of identical queries and rarely changing tables. See the
# "Qcache_lowmem_prunes" status variable to check if the current value
# is high enough for your load.
# Note: In case your tables change very often or if your queries are
# textually different every time, the query cache may result in a
# slowdown instead of a performance improvement.
query_cache_size=0

# The number of open tables for all threads. Increasing this value
# increases the number of file descriptors that mysqld requires.
# Therefore you have to make sure to set the amount of open files
# allowed to at least 4096 in the variable "open-files-limit" in
# section [mysqld_safe]
table_cache=256

# Maximum size for internal (in-memory) temporary tables. If a table
# grows larger than this value, it is automatically converted to disk
# based table This limitation is for a single table. There can be many
# of them.
tmp_table_size=205M


# How many threads we should keep in a cache for reuse. When a client
# disconnects, the client's threads are put in the cache if there aren't
# more than thread_cache_size threads from before.  This greatly reduces
# the amount of thread creations needed if you have a lot of new
# connections. (Normally this doesn't give a notable performance
# improvement if you have a good thread implementation.)
thread_cache_size=8

#*** MyISAM Specific options

# The maximum size of the temporary file MySQL is allowed to use while
# recreating the index (during REPAIR, ALTER TABLE or LOAD DATA INFILE.
# If the file-size would be bigger than this, the index will be created
# through the key cache (which is slower).
myisam_max_sort_file_size=100G

# If the temporary file used for fast index creation would be bigger
# than using the key cache by the amount specified here, then prefer the
# key cache method.  This is mainly used to force long character keys in
# large tables to use the slower key cache method to create the index.
myisam_sort_buffer_size=410M

# Size of the Key Buffer, used to cache index blocks for MyISAM tables.
# Do not set it larger than 30% of your available memory, as some memory
# is also required by the OS to cache rows. Even if you're not using
# MyISAM tables, you should still set it to 8-64M as it will also be
# used for internal temporary disk tables.
key_buffer_size=354M

# Size of the buffer used for doing full table scans of MyISAM tables.
# Allocated per thread, if a full scan is needed.
read_buffer_size=64K
read_rnd_buffer_size=256K

# This buffer is allocated when MySQL needs to rebuild the index in
# REPAIR, OPTIMZE, ALTER table statements as well as in LOAD DATA INFILE
# into an empty table. It is allocated per thread so be careful with
# large settings.
sort_buffer_size=256K


#*** INNODB Specific options ***


# Use this option if you have a MySQL server with InnoDB support enabled
# but you do not plan to use it. This will save memory and disk space
# and speed up some things.
#skip-innodb

# Additional memory pool that is used by InnoDB to store metadata
# information.  If InnoDB requires more memory for this purpose it will
# start to allocate it from the OS.  As this is fast enough on most
# recent operating systems, you normally do not need to change this
# value. SHOW INNODB STATUS will display the current amount used.
innodb_additional_mem_pool_size=15M

# If set to 1, InnoDB will flush (fsync) the transaction logs to the
# disk at each commit, which offers full ACID behavior. If you are
# willing to compromise this safety, and you are running small
# transactions, you may set this to 0 or 2 to reduce disk I/O to the
# logs. Value 0 means that the log is only written to the log file and
# the log file flushed to disk approximately once per second. Value 2
# means the log is written to the log file at each commit, but the log
# file is only flushed to disk approximately once per second.
innodb_flush_log_at_trx_commit=1

# The size of the buffer InnoDB uses for buffering log data. As soon as
# it is full, InnoDB will have to flush it to disk. As it is flushed
# once per second anyway, it does not make sense to have it very large
# (even with long transactions).
innodb_log_buffer_size=7M

# InnoDB, unlike MyISAM, uses a buffer pool to cache both indexes and
# row data. The bigger you set this the less disk I/O is needed to
# access data in tables. On a dedicated database server you may set this
# parameter up to 80% of the machine physical memory size. Do not set it
# too large, though, because competition of the physical memory may
# cause paging in the operating system.  Note that on 32bit systems you
# might be limited to 2-3.5G of user level memory per process, so do not
# set it too high.
innodb_buffer_pool_size=686M

# Size of each log file in a log group. You should set the combined size
# of log files to about 25%-100% of your buffer pool size to avoid
# unneeded buffer pool flush activity on log file overwrite. However,
# note that a larger logfile size will increase the time needed for the
# recovery process.
innodb_log_file_size=100M

# Number of threads allowed inside the InnoDB kernel. The optimal value
# depends highly on the application, hardware as well as the OS
# scheduler properties. A too high value may lead to thread thrashing.
innodb_thread_concurrency=8

And this is the code that we have used in our script to connect with mysql:

public function MySqlConnect()
{
    static $MySqli;

    if (!isset($MySqli))
    {
        $MySqli = @new mysqli($this->DbHost, $this->DbUser, $this->Dbpassword, $this->Db);
    }
    return $MySqli;
}

Please help us to understand what is wrong with the my.ini file or connection script which is causing 100% cpu usage for mysql or is there something different that we need to change.

Thanks.

douju7765
douju7765 记得关闭你的连接。内存泄漏会导致很多问题。如果您的mysql对连接没有严格的限制,那么您将遇到很多问题。
5 年多之前 回复
doubi1797
doubi1797 你好。它不是导致问题的PHP。通常它的SQL查询很长。尽量不要使用@,而是使用ini_set('display_errors','1');看到潜在的问题。请发布需要很长时间才能执行的sql
5 年多之前 回复
dongpangzan6425
dongpangzan6425 这个问题会更适合dba.stackexchange.com吗?
5 年多之前 回复
doubingqi5829
doubingqi5829 很难说只有这个,你能提供你使用的查询以及你拥有的表结构(索引最重要)吗?恕我直言,这是问题的核心
5 年多之前 回复

1个回答



MySQL高CPU与PHP无关。 您首先需要了解高CPU的原因然后再进行处理。 执行以下操作以跟踪实际原因</ p>


  1. 启用 slow_query.log </ strong>,查找非常适合优化的查询。 slow_query.log中的一些查询可能会占用大量CPU </ p> </ li>

  2. 如果有任何线索,请检查这些查询的状态</ p>

    SHOW ENGINE INNODB状态\ G;

    显示完整的流程列表; </ code> </ p> </ li>

  3. 确保所有表格去碎片化</ strong> </ p> </ li>

  4. 增加 innodb_buffer_pool_size </ code>以便有更多缓存</ p> </ li>

  5. 同时调整以下参数。 如果可能,使用 mysqltuner.pl </ strong>来获取建议值以在MySQL配置中调整这些参数</ p>

    innodb_fast_shutdown = 0
    innodb_log_buffer_size
    innodb_log_file_size
    innodb_flush_method = O_DIRECT

    query_cache_size = 0 </ code> </ p> </ li>
    </ ol>
    </ div>

展开原文

原文

MySQL high CPU is not related to PHP. You first need to catch the reason for high CPU and then work on that. Do the following to trace the actual reason

  1. Enable slow_query.log , Find queries that are a great candidate for optimization. Some queries in slow_query.log may utilize lot of CPU

  2. Check the status of these if you get any clue

    SHOW ENGINE INNODB STATUS\G; SHOW FULL PROCESSLIST;

  3. Make sure all your tables are de-fragmented

  4. Increase the innodb_buffer_pool_size so that there is more caching

  5. Also tune the following parameters. If possible use mysqltuner.pl to get the suggested values to tune these parameters in MySQL configuration

    innodb_fast_shutdown=0 innodb_log_buffer_size innodb_log_file_size innodb_flush_method=O_DIRECT query_cache_size=0

douyu9012
douyu9012 没有帮助这个答案请另一个答案
5 年多之前 回复
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