I'm not sure if stack is the right place to ask this, but I recently upgraded to Percona 5.6 from 5.5 and my memory usage has skyrocketed!
This is from PS:
mysql 4598 0.0 29.5 1583356 465312 ? Sl Oct17 9:07 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib6
I'm on a dedicated VSS
My server only has a gig of ram...how is this only memory usage only 30% according to PS?
I have my ram set in the config to be less than this, and when I run MySQLTuner i get:
[OK] Maximum possible memory usage: 338.9M (22% of installed RAM)
So how am I using almost 500MB of physical memory and over a gig and a half of virtual?
Is this a bug in mySQL or something with my server?
found out that in mysql 5.6 performance_schema is on by default. It was disabled by default prior in 5.5 and before. It has been enabled by default since 5.6.6
performance_schema=off to my config file fixes the issue.
I'd imagine anyone who doesn't have the memory to be running performance_schema would not be using it anyway.
This might affect other distros of mysql 5.6.6 as well.
I had this problem and fixing a few (increased) cache values in MySQL.ini sorted the problem out.
table_definition_cache - set to 400
From "http://bugs.mysql.com/bug.php?id=68287" where this is discussed
Yes, there are thresholds based on table_open_cache and table_definition_cache and max_connections and crossing the thresholds produces a big increase in RAM used. The thresholds work by first deciding if the server size is small, medium or large.
Small: all three are same as or less than defaults (2000, 400, 151).
Large: any of the three is more than twice the default.
Medium: others.
From memory. mine was set to 2000+ and dropping it sorted the problem.
What helped me was on CentOS was changing the memory allocator:
yum install jemalloc-devel
and add to my.cnf:
[mysqld_safe]
malloc-lib = /usr/lib64/libjemalloc.so.1
Related
I have a 2GB RAM machine running MySQL.
When I set my innodb_buffer_pool_size in my.cnf to "1G", the MySQL process uses around 1.3GB which is the expected behaviour. However, when I set it to "1000M" the RAM runs out and the MySQL process crashes.
According to the documentation "M" stands for Megabytes and "G" for Gigabytes. So, 1000M should be the same as 1G. Is there anything I am missing?
For only 2GB of RAM, neither 1000M nor 1G is a reasonable value for that setting. When MySQL swaps, it gets a lot slower. So, it is better to avoid swapping than to have a high value for the buffer_pool. Recommend only 500M.
I used Mysql 5.5.57 and used innodb
Currency I face performance related issues due to which our system gets crashed.
and got many errors like lockwait time out and deadlock problems on many tables.
I trying to solve that.
but i think if i change my innodb configuration default setting then also system performance gets increased but i dont know what type of variable needs to change so please help me
below is our default innodb configuration setting:
The below is the settings in my.cnf:
innodb_file_format=barracuda
innodb_file_format_max=barracuda
innodb_file_per_table=1
query-cache-size = 64M
thread_cache_size = 8
default-time-zone = '+05:30'
query_cache_limit = 10M
character_set_server=utf8mb4
collation_server=utf8mb4_general_ci
innodb_thread_concurrency=8
key_buffer_size=183500800
group_concat_max_len=50000
innodb_log_file_size=178257920
#innodb_lock_wait_timeout=150
innodb_buffer_pool_size=134 MB
innodb_thread_concurrency=8
innodb_thread_sleep_delay=10000
innodb_concurrency_tickets=500
innodb lock_wait_time_out=150
We have 132GB Ram on the server with 2 processors and each has 6 cores.
16GB should be more than enough for MySql.
please help to set proper variables size for each parameter i provided here
I suggest you read this atrticle https://www.percona.com/blog/2013/09/20/innodb-performance-optimization-basics-updated/
You will find example for each variable there, i think this is what you need.
I've got a significant performance boost by setting
innodb_flush_log_at_trx_commit=0
innodb_buffer_pool_size=2G
innodb_log_file_size=256M
innodb_log_buffer_size=8M
innodb_buffer_pool_instances=1
Specifically, innodb_flush_log_at_trx_commit=0 speeds up loading a dump file from minutes to seconds! This setting is not recommended for "mission-critical" environments but is pretty fine for a development machine.
I'm running a NodeJS with MySQL (InnoDB) for a game server (player info, savedata, stuff). Server is HTTP(S) based so nothing realtime.
I'm having these weird spikes as you can see from the graphs below (first graph is requests/sec and last graph is queries/sec)
On the response time graph you can see max response times with purple and avg response times with blue. Even with those 10-20k peaks avg stays at 50-100ms as do 95% of the requests.
I've been digging around and found that the slow queries are nothing special. Usually update query with savedata (blob of ~2kb) or player profile update which modifies like username or so. No joins or anything like that. We're talking about tables with less than 100k rows.
Server is running in Azure on Ubuntu 14.04 with MySQL 5.7 using 4 cores and 7GB of RAM.
MySQL settings:
innodb_buffer_pool_size=4G
innodb_log_file_size=1G
innodb_buffer_pool_instances=4
innodb_log_buffer_size=4M
query_cache_type=0
tmp_table_size=64M
max_heap_table_size=64M
sort_buffer_size=32M
wait_timeout=300
interactive_timeout=300
innodb_file_per_table=ON
Edit: It turned out that the problem was never MySQL performance but Node.js performance before the SQL queries. More info here: Node.js multer and body-parser sometimes extremely slow
check your swappiness (suppose to be 0 mysql machines maximizing ram usage):
> sysctl -A|grep swap
vm.swappiness = 0
with only 7G of RAM and 4G of just buffer pool, your machine will swap if swappiness is not zero.
could you post your swap graph and used memory. 4G buffer is "over the edge" for 7G ram. For 8G ram, I would give 3G as you have +1G on everything else mysql wise + 2G on OS.
Also you have 1G for transaction log file and I assume you have two log files. Do you have so many writes to have such large files? You can use this guide: https://www.percona.com/blog/2008/11/21/how-to-calculate-a-good-innodb-log-file-size/
I have setup with Linux, Debian Jessie with Mysql 5.7.13 installed.
I have set following settings in
my.cnf: default_storage_engine= innodb, innodb_buffer_pool_size= 44G
When I start MySQL I manually set max_connections with SET GLOBAL max_connections = 1000;
Then I trigger my loadtest that sends a lot of traffic to the DB server which mostly consists of slow/bad queries.
The result I expected was that I would reach close to 1000 connections but somehow MySQL limits it to 462 connections and I can not find the setting that is responsible for this limit. We are not even close to maxing out the CPU or Memory.
If you have any idea or could point me in a direction where you think the error might be it would be really helpful.
What loadtest did you use? Are you sure that it can utilize about thousands of connections?
You may maxing out your server resources in the disk IO area, especially if you're talking about lot of slow/bad queries. Did you check for disk utilization on your server?
Even if your InnoDB pool size is large your DB still need to read your DB to the cache first, and if your entire DB is large it will not help you.
I can recommend you to perform such a test once more time and track your disk performance during loadtest using iostat or iotop utility.
Look here for more examples of the server performance troubleshooting.
I found the issue, it was du to limitation of Apache server, there is a "hidden" setting inside /etc/apache2/mods-enabled/mpm_prefork.conf which will overwrite setting inside /etc/apache2/apache2.conf
Thank you!
This question already has answers here:
MySQL maximum memory usage
(7 answers)
Closed 9 years ago.
I have MySQL installed on a VPS Windows 2008 Web Server with 1GB of memory.
Is there a way of setting a maximum memory usage limit for MYSQL.
I have workbench installed if it can be done through that.
Many Thanks
John
If you really want to impose a hard limit, you could do so, but you'd have to do it at the OS level as there is no built-in setting. In linux, you could utilize ulimit, but you'd likely have to modify the way MySQL starts in order to impose this.
The best solution is to tune your server down, so that a combination of the usual MySQL memory settings will result in generally lower memory usage by your MySQL installation. This will of course have a negative impact on the performance of your database, but some of the settings you can tweak in my.ini are:
key_buffer_size
query_cache_size
query_cache_limit
table_cache
max_connections
tmp_table_size
innodb_buffer_pool_size
To Plot memory usage in Linux you can easily use a script
while true
do
date >> ps.log
ps aux | grep mysqld >> ps.log
sleep 60
done
if you are trying to Check for Table Cache Related Allocations
Run “FLUSH TABLES” and see whenever memory usage goes down.
Note though because of how memory is allocated from OS you might not
see “VSZ” going down. What you might see instead is flushing tables
regularly or reducing table cache reduces memory consumption to be
withing the reason.
It is often helpful to check how much memory Innodb has allocated. In fact this is often one of the first things I do as it is least intrusive. Run SHOW ENGINE INNODB STATUS and look for memory information block