mysql耗內(nèi)存嗎？應(yīng)該怎么處理？

　　mysql耗內(nèi)存嗎?很多人都說(shuō)MySQL占用了很大的虛擬內(nèi)存，那么這個(gè)問(wèn)題應(yīng)該怎么解決呢?下面是學(xué)習(xí)啦小編收集整理的一些方法，現(xiàn)在分享給大家!

　　解決mysql耗內(nèi)存的具體方法一：

　　在分析的過(guò)程中發(fā)現(xiàn)最耗內(nèi)存的是MySQL，其中近1GB的內(nèi)存被它吞了，而且不在任務(wù)管理器體現(xiàn)出來(lái)。這個(gè)數(shù)據(jù)庫(kù)軟件是EMS要用到了，所以必須要運(yùn)行。這個(gè)軟件在安裝的時(shí)候會(huì)根據(jù)機(jī)器的實(shí)際內(nèi)存自動(dòng)進(jìn)行配置，PC機(jī)物理內(nèi)存越多，它默認(rèn)占有的內(nèi)存就越多，難怪3GB的內(nèi)存被它給吞了近1GB。

　　優(yōu)化方法：

　　1. 退出EMS client&server

　　2. 在CMD里運(yùn)行：net stop mysql

　　3. 找到MySQL\MySQL Server的安裝目錄，里面有個(gè)my.ini文件，參考附件的配置對(duì)參數(shù)query_cache_size tmp_table_size myisam_sort_buffer_size key_buffer_size innodb_buffer_pool_size進(jìn)行修改，注意不要改動(dòng)innodb_log_file_size，修改前備份my.ini

　　4. 在CMD里運(yùn)行：net start mysql，如果提示成功，則說(shuō)明修改的參數(shù)沒(méi)有什么問(wèn)題，如果失敗，重新調(diào)整一下上面的參數(shù)

　　5. 找到EMS 安裝目錄runGUI.bat runServer.bat腳本，找到-Xmx700m，改為-Xmx256m，注意修改前備份這兩個(gè)文件，感謝Liping Sun提供幫助

　　6. 重新運(yùn)行EMS

　　前后對(duì)比，對(duì)于3GB的PC，發(fā)現(xiàn)可以節(jié)省近1GB的內(nèi)存。對(duì)于2GB的PC，也可以節(jié)省600-800MB。優(yōu)化后發(fā)現(xiàn)EMS啟動(dòng)稍微慢一些，但是其它的軟件運(yùn)行速度提高了很多，不在經(jīng)常出現(xiàn)卡機(jī)現(xiàn)象了。如果在運(yùn)行過(guò)程中發(fā)現(xiàn)EMS特別慢的話，自己也可以適當(dāng)放大上面提到的一些參數(shù)。

　　my.ini

　　# 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="D:/Program Files/MySQL/MySQL Server 5.1/"

　　#Path to the database root

　　datadir="C:/Documents and Settings/All Users/Application Data/MySQL/MySQL Server 5.1/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=1510

　　# 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=16M

　　# 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=3020

　　# 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=4M

　　# 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=64

　　#*** 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=4M

　　# 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=16M

　　# 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=9M

　　# 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=5M

　　# 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=32M

　　# 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=88M

　　# 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

　　解決mysql耗內(nèi)存的具體方法二：

　　更改后如下：

　　innodb_buffer_pool_size=576M ->256M InnoDB引擎緩沖區(qū)占了大頭，首要就是拿它開(kāi)刀

　　query_cache_size=100M ->16M 查詢緩存

　　tmp_table_size=102M ->64M 臨時(shí)表大小

　　key_buffer_size=256m ->32M

　　重啟mysql服務(wù)后，虛擬內(nèi)存降到200以下.

　　另外mysql安裝目錄下有幾個(gè)文件：my-huge.ini 、my-large.ini、my-medium.ini...這幾個(gè)是根據(jù)內(nèi)存大小作的建議配置，新手在設(shè)置的時(shí)候也可以參考一下。

　　2G內(nèi)存的MYSQL數(shù)據(jù)庫(kù)服務(wù)器 my.ini優(yōu)化 (my.ini)

　　2G內(nèi)存,針對(duì)站少,優(yōu)質(zhì)型的設(shè)置,試驗(yàn)特：

　　table_cache=1024 物理內(nèi)存越大,設(shè)置就越大.默認(rèn)為2402,調(diào)到512-1024最佳

　　innodb_additional_mem_pool_size=8M 默認(rèn)為2M

　　innodb_flush_log_at_trx_commit=0 等到innodb_log_buffer_size列隊(duì)滿后再統(tǒng)一儲(chǔ)存,默認(rèn)為1

　　innodb_log_buffer_size=4M 默認(rèn)為1M

　　innodb_thread_concurrency=8 你的服務(wù)器CPU有幾個(gè)就設(shè)置為幾,默認(rèn)為8

　　key_buffer_size=256M 默認(rèn)為218 調(diào)到128最佳

　　tmp_table_size=64M 默認(rèn)為16M 調(diào)到64-256最掛

　　read_buffer_size=4M 默認(rèn)為64K

　　read_rnd_buffer_size=16M 默認(rèn)為256K

　　sort_buffer_size=32M 默認(rèn)為256K

　　max_connections=1024 默認(rèn)為1210

　　試驗(yàn)一：

　　table_cache=512或1024

　　innodb_additional_mem_pool_size=2M

　　innodb_flush_log_at_trx_commit=0

　　innodb_log_buffer_size=1M

　　innodb_thread_concurrency=8 你的服務(wù)器CPU有幾個(gè)就設(shè)置為幾,默認(rèn)為8

　　key_buffer_size=128M

　　tmp_table_size=128M

　　read_buffer_size=64K或128K

　　read_rnd_buffer_size=256K

　　sort_buffer_size=512K

　　max_connections=1024

　　試驗(yàn)二：

　　table_cache=512或1024

　　innodb_additional_mem_pool_size=8M

　　innodb_flush_log_at_trx_commit=0

　　innodb_log_buffer_size=4M

　　innodb_thread_concurrency=8

　　key_buffer_size=128M

　　tmp_table_size=128M

　　read_buffer_size=4M

　　read_rnd_buffer_size=16M

　　sort_buffer_size=32M

　　max_connections=1024

　　一般：

　　table_cache=512

　　innodb_additional_mem_pool_size=8M

　　innodb_flush_log_at_trx_commit=0

　　innodb_log_buffer_size=4M

　　innodb_thread_concurrency=8

　　key_buffer_size=128M

　　tmp_table_size=128M

　　read_buffer_size=4M

　　read_rnd_buffer_size=16M

　　sort_buffer_size=32M

　　max_connections=1024

　　經(jīng)過(guò)測(cè)試.沒(méi)有特殊情況,最好還是用默認(rèn)的.

　　2G內(nèi)存,針對(duì)站多,抗壓型的設(shè)置,最佳：

　　table_cache=1024 物理內(nèi)存越大,設(shè)置就越大.默認(rèn)為2402,調(diào)到512-1024最佳

　　innodb_additional_mem_pool_size=4M 默認(rèn)為2M

　　innodb_flush_log_at_trx_commit=1

　　(設(shè)置為0就是等到innodb_log_buffer_size列隊(duì)滿后再統(tǒng)一儲(chǔ)存,默認(rèn)為1)

　　innodb_log_buffer_size=2M 默認(rèn)為1M

　　innodb_thread_concurrency=8 你的服務(wù)器CPU有幾個(gè)就設(shè)置為幾,建議用默認(rèn)一般為8

　　key_buffer_size=256M 默認(rèn)為218 調(diào)到128最佳

　　tmp_table_size=64M 默認(rèn)為16M 調(diào)到64-256最掛

　　read_buffer_size=4M 默認(rèn)為64K

　　read_rnd_buffer_size=16M 默認(rèn)為256K

　　sort_buffer_size=32M 默認(rèn)為256K

　　max_connections=1024 默認(rèn)為1210

　　thread_cache_size=120 默認(rèn)為60

　　query_cache_size=64M

　　優(yōu)化mysql數(shù)據(jù)庫(kù)性能的十個(gè)參數(shù)

　　(1)、max_connections：

　　允許的同時(shí)客戶的數(shù)量。增加該值增加 mysqld 要求的文件描述符的數(shù)量。這個(gè)數(shù)字應(yīng)該增加，否則，你將經(jīng)?？吹?too many connections 錯(cuò)誤。 默認(rèn)數(shù)值是100，我把它改為1024 。

　　(2)、record_buffer：

　　每個(gè)進(jìn)行一個(gè)順序掃描的線程為其掃描的每張表分配這個(gè)大小的一個(gè)緩沖區(qū)。如果你做很多順序掃描，你可能想要增加該值。默認(rèn)數(shù)值是131072(128k)，我把它改為16773120 (16m)

　　(3)、key_buffer_size：

　　索引塊是緩沖的并且被所有的線程共享。key_buffer_size是用于索引塊的緩沖區(qū)大小，增加它可得到更好處理的索引(對(duì)所有讀和多重寫(xiě))，到你能負(fù)擔(dān)得起那樣多。如果你使它太大，系統(tǒng)將開(kāi)始換頁(yè)并且真的變慢了。默認(rèn)數(shù)值是8388600(8m)，我的mysql主機(jī)有2gb內(nèi)存，所以我把它改為 402649088(400mb)。

　　4)、back_log：

　　要求 mysql 能有的連接數(shù)量。當(dāng)主要mysql線程在一個(gè)很短時(shí)間內(nèi)得到非常多的連接請(qǐng)求，這就起作用，然后主線程花些時(shí)間(盡管很短)檢查連接并且啟動(dòng)一個(gè)新線程。

　　back_log 值指出在mysql暫時(shí)停止回答新請(qǐng)求之前的短時(shí)間內(nèi)多少個(gè)請(qǐng)求可以被存在堆棧中。只有如果期望在一個(gè)短時(shí)間內(nèi)有很多連接，你需要增加它，換句話說(shuō)，這值對(duì)到來(lái)的tcp/ip連接的偵聽(tīng)隊(duì)列的大小。你的操作系統(tǒng)在這個(gè)隊(duì)列大小上有它自己的限制。試圖設(shè)定back_log高于你的操作系統(tǒng)的限制將是無(wú)效的。

　　當(dāng)你觀察你的主機(jī)進(jìn)程列表，發(fā)現(xiàn)大量 264084 | unauthenticated user | xxx.xxx.xxx.xxx | null | connect | null | login | null 的待連接進(jìn)程時(shí)，就要加大 back_log 的值了。默認(rèn)數(shù)值是50，我把它改為500。

　　(5)、interactive_timeout：

　　服務(wù)器在關(guān)閉它前在一個(gè)交互連接上等待行動(dòng)的秒數(shù)。一個(gè)交互的客戶被定義為對(duì) mysql_real_connect()使用 client_interactive 選項(xiàng)的客戶。 默認(rèn)數(shù)值是28800，我把它改為7200。

　　(6)、sort_buffer：

　　每個(gè)需要進(jìn)行排序的線程分配該大小的一個(gè)緩沖區(qū)。增加這值加速order by或group by操作。默認(rèn)數(shù)值是2097144(2m)，我把它改為 16777208 (16m)。

　　(7)、table_cache：

　　為所有線程打開(kāi)表的數(shù)量。增加該值能增加mysqld要求的文件描述符的數(shù)量。mysql對(duì)每個(gè)唯一打開(kāi)的表需要2個(gè)文件描述符。默認(rèn)數(shù)值是64，我把它改為512。

　　(8)、thread_cache_size：

　　可以復(fù)用的保存在中的線程的數(shù)量。如果有，新的線程從緩存中取得，當(dāng)斷開(kāi)連接的時(shí)候如果有空間，客戶的線置在緩存中。如果有很多新的線程，為了提高性能可以這個(gè)變量值。通過(guò)比較 connections 和 threads_created 狀態(tài)的變量，可以看到這個(gè)變量的作用。我把它設(shè)置為 80。

　　(9)mysql的搜索功能

　　用mysql進(jìn)行搜索，目的是能不分大小寫(xiě)，又能用中文進(jìn)行搜索

　　只需起動(dòng)mysqld時(shí)指定 --default-character-set=gb2312

　　(10)、wait_timeout：

　　服務(wù)器在關(guān)閉它之前在一個(gè)連接上等待行動(dòng)的秒數(shù)。 默認(rèn)數(shù)值是28800，我把它改為7200。

　　注：參數(shù)的調(diào)整可以通過(guò)修改 /etc/my.cnf 文件并重啟 mysql 實(shí)現(xiàn)。這是一個(gè)比較謹(jǐn)慎的工作，上面的結(jié)果也僅僅是我的一些看法，你可以根據(jù)你自己主機(jī)的硬件情況(特別是內(nèi)存大小)進(jìn)一步修改。