mysql耗內存嗎？應該怎么處理？

時間：2016-08-22 16:01:44 本達868由分享

mysql耗內存嗎？應該怎么處理？

　　mysql耗內存嗎?很多人都說MySQL占用了很大的虛擬內存，那么這個問題應該怎么解決呢?下面是學習啦小編收集整理的一些方法，現在分享給大家!

　　解決mysql耗內存的具體方法一：

　　在分析的過程中發現最耗內存的是MySQL，其中近1GB的內存被它吞了，而且不在任務管理器體現出來。這個數據庫軟件是EMS要用到了，所以必須要運行。這個軟件在安裝的時候會根據機器的實際內存自動進行配置，PC機物理內存越多，它默認占有的內存就越多，難怪3GB的內存被它給吞了近1GB。

　　優化方法：

　　1. 退出EMS client&server

　　2. 在CMD里運行：net stop mysql

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

　　4. 在CMD里運行：net start mysql，如果提示成功，則說明修改的參數沒有什么問題，如果失敗，重新調整一下上面的參數

　　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文件，感謝Liping Sun提供幫助

　　6. 重新運行EMS

　　前后對比，對于3GB的PC，發現可以節省近1GB的內存。對于2GB的PC，也可以節省600-800MB。優化后發現EMS啟動稍微慢一些，但是其它的軟件運行速度提高了很多，不在經常出現卡機現象了。如果在運行過程中發現EMS特別慢的話，自己也可以適當放大上面提到的一些參數。

　　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耗內存的具體方法二：

　　更改后如下：

　　innodb_buffer_pool_size=576M ->256M InnoDB引擎緩沖區占了大頭，首要就是拿它開刀

　　query_cache_size=100M ->16M 查詢緩存

　　tmp_table_size=102M ->64M 臨時表大小

　　key_buffer_size=256m ->32M

　　重啟mysql服務后，虛擬內存降到200以下.

　　另外mysql安裝目錄下有幾個文件：my-huge.ini 、my-large.ini、my-medium.ini...這幾個是根據內存大小作的建議配置，新手在設置的時候也可以參考一下。

　　2G內存的MYSQL數據庫服務器 my.ini優化 (my.ini)

　　2G內存,針對站少,優質型的設置,試驗特：

　　table_cache=1024 物理內存越大,設置就越大.默認為2402,調到512-1024最佳

　　innodb_additional_mem_pool_size=8M 默認為2M

　　innodb_flush_log_at_trx_commit=0 等到innodb_log_buffer_size列隊滿后再統一儲存,默認為1

　　innodb_log_buffer_size=4M 默認為1M

　　innodb_thread_concurrency=8 你的服務器CPU有幾個就設置為幾,默認為8

　　key_buffer_size=256M 默認為218 調到128最佳

　　tmp_table_size=64M 默認為16M 調到64-256最掛

　　read_buffer_size=4M 默認為64K

　　read_rnd_buffer_size=16M 默認為256K

　　sort_buffer_size=32M 默認為256K

　　max_connections=1024 默認為1210

　　試驗一：

　　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 你的服務器CPU有幾個就設置為幾,默認為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

　　經過測試.沒有特殊情況,最好還是用默認的.

　　2G內存,針對站多,抗壓型的設置,最佳：

　　table_cache=1024 物理內存越大,設置就越大.默認為2402,調到512-1024最佳

　　innodb_additional_mem_pool_size=4M 默認為2M

　　innodb_flush_log_at_trx_commit=1

　　(設置為0就是等到innodb_log_buffer_size列隊滿后再統一儲存,默認為1)

　　innodb_log_buffer_size=2M 默認為1M

　　innodb_thread_concurrency=8 你的服務器CPU有幾個就設置為幾,建議用默認一般為8

　　key_buffer_size=256M 默認為218 調到128最佳

　　tmp_table_size=64M 默認為16M 調到64-256最掛

　　read_buffer_size=4M 默認為64K

　　read_rnd_buffer_size=16M 默認為256K

　　sort_buffer_size=32M 默認為256K

　　max_connections=1024 默認為1210

　　thread_cache_size=120 默認為60

　　query_cache_size=64M

　　優化mysql數據庫性能的十個參數

　　(1)、max_connections：

　　允許的同時客戶的數量。增加該值增加 mysqld 要求的文件描述符的數量。這個數字應該增加，否則，你將經常看到 too many connections 錯誤。默認數值是100，我把它改為1024 。

　　(2)、record_buffer：

　　每個進行一個順序掃描的線程為其掃描的每張表分配這個大小的一個緩沖區。如果你做很多順序掃描，你可能想要增加該值。默認數值是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大小，增加它可得到更好處理的索引(對所有讀和多重寫)，到你能負擔得起那樣多。如果你使它太大，系統將開始換頁并且真的變慢了。默認數值是8388600(8m)，我的mysql主機有2gb內存，所以我把它改為 402649088(400mb)。

　　4)、back_log：

　　要求 mysql 能有的連接數量。當主要mysql線程在一個很短時間內得到非常多的連接請求，這就起作用，然后主線程花些時間(盡管很短)檢查連接并且啟動一個新線程。

　　back_log 值指出在mysql暫時停止回答新請求之前的短時間內多少個請求可以被存在堆棧中。只有如果期望在一個短時間內有很多連接，你需要增加它，換句話說，這值對到來的tcp/ip連接的偵聽隊列的大小。你的操作系統在這個隊列大小上有它自己的限制。試圖設定back_log高于你的操作系統的限制將是無效的。

　　(5)、interactive_timeout：

　　服務器在關閉它前在一個交互連接上等待行動的秒數。一個交互的客戶被定義為對 mysql_real_connect()使用 client_interactive 選項的客戶。默認數值是28800，我把它改為7200。

　　(6)、sort_buffer：

　　每個需要進行排序的線程分配該大小的一個緩沖區。增加這值加速order by或group by操作。默認數值是2097144(2m)，我把它改為 16777208 (16m)。

　　(7)、table_cache：

　　為所有線程打開表的數量。增加該值能增加mysqld要求的文件描述符的數量。mysql對每個唯一打開的表需要2個文件描述符。默認數值是64，我把它改為512。

　　(8)、thread_cache_size：

　　可以復用的保存在中的線程的數量。如果有，新的線程從緩存中取得，當斷開連接的時候如果有空間，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變量值。通過比較 connections 和 threads_created 狀態的變量，可以看到這個變量的作用。我把它設置為 80。

　　(9)mysql的搜索功能

　　用mysql進行搜索，目的是能不分大小寫，又能用中文進行搜索

　　只需起動mysqld時指定 --default-character-set=gb2312

　　(10)、wait_timeout：

　　服務器在關閉它之前在一個連接上等待行動的秒數。默認數值是28800，我把它改為7200。

　　注：參數的調整可以通過修改 /etc/my.cnf 文件并重啟 mysql 實現。這是一個比較謹慎的工作，上面的結果也僅僅是我的一些看法，你可以根據你自己主機的硬件情況(特別是內存大小)進一步修改。

mysql耗內存嗎？應該怎么處理？

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