问题
I have recently started on a PoC project wherein we are developing a small web app. The initial setup is done on a micro instance from AWS. We are on rails+mysql stack.
After installing/running MySQL, I see that about 500+ MB RAM has been consumed already; leaving quite less for rest of the systems (micro instances have barely 620 MB RAM).
Our app is fairly simple at this stage. Can I do something to reduce the memory consumed by MySQL server?
Appreciate the help.
回答1:
Change this setting in the MySQL configuration file (my.cnf)
key_buffer = 8M
max_connections = 30 # Limit connections
query_cache_size = 8M # try 4m if not enough
query_cache_limit = 512K
thread_stack = 128K
回答2:
In your my.cnf file:
performance_schema = 0
And restart mysql. This should chop memory usage dramatically if you previously had it on.
2016 Edit: From MySQL 5.7.8 onwards, the above is not enough to free your memory of performance schema data:
As of MySQL 5.7.8, even when the Performance Schema is disabled, it continues to populate the global_variables, session_variables, global_status, and session_status tables.
(source)
To prevent this behaviour, set show_compatibility_56 to 1 in addition to performance_schema. That is to say, your my.cnf changes should look like:
performance_schema = 0
show_compatibility_56 = 1
回答3:
Just to add to the other answer. I recently had this problem myself with the Amazon micro instance (not Ubuntu). The my.cnf file is almost empty so what I did was this:
cp /etc/my.cnf /etc/my.cnf.orig
cp /usr/share/mysql/my-medium.cnf /etc/my.cnf
Edit my.cnf and enable the innodb lines if applicable. Restart mysqld.
Also the micro instance has no swap, that might be a problem..
SWAPFILE=/mnt/swapfile.swap
dd if=/dev/zero of=$SWAPFILE bs=1M count=512
mkswap $SWAPFILE
swapon $SWAPFILE
Then in /etc/rc.local add:
swapon /mnt/swapfile.swap
To save memory in ruby you might want to use ruby enterprise:
bash < <(curl -s https://raw.github.com/wayneeseguin/rvm/master/binscripts/rvm-installer)
gpasswd -a root rvm
source /etc/profile.d/rvm.sh
rvm get head
rvm reload
rvm install ree
rvm --default use ree
回答4:
I have a server with only 500mb ram and found that mysql started using a lot of ram as my tables got larger. After playing with a bunch of the settings, what reduced memory usage for me was to convert all my tables to MyISAM. If you dont need the features of innodb converting tables to MyISAM helps quite a bit. You can convert tables like this :
ALTER TABLE test.mytable ENGINE=MyISAM;
After this change I found that memory usage decreased by 20%. To get a further reduction in memory usage you can convert ALL of your tables to MyISAM and then turn off innodb support in mysql altogether. This reduced my memory usage by 50%.
You can do this by adding :
[mysqld]
default_storage_engine=myisam
innodb=OFF
and then restarting mysql.
来源：https://stackoverflow.com/questions/10676753/reducing-memory-consumption-of-mysql-on-ubuntuaws-micro-instance