I'm running a distributed app in the cloud where clients keep open multiple long-running connections to a MySQL (Percona) server.
After updating to the latest Percona release, the maximum number of simultaneously connected clients has dropped significantly. In the past, with the previous Percona version, it was used successfully with up to 8K connections, now it struggles to get above 3K.
By "struggles" I mean that when the connection bottleneck has been reached, connecting to MySQL times out even in the command line. When I do manage to connect, show processlist doesn't show any hanging queries or locks. So the connections that are established work just fine. The Apache webserver serving the PHP webapp used to monitor the project also hangs indefinitely.
Here's the my.cnf I use, patched together from various guides.
[mysqld]
open_files_limit = 16384
table_open_cache = 16384
character_set_server = utf8mb4
max_connections = 16384
expire_logs_days = 10
max_binlog_size = 100M
innodb_open_files = 16384
innodb_file_per_table = 1
innodb_read_io_threads = 4
innodb_write_io_threads = 4
innodb_thread_concurrency = 0
innodb_log_file_size = 128M
innodb_open_files = 4000
innodb_flush_method = O_DIRECT
innodb_buffer_pool_instances = 1
thread_pool_size = 16
local_infile = 1
skip-name-resolve
thread_cache_size = 16384
thread_handling = pool-of-threads
innodb_buffer_pool_size = 512M
innodb_buffer_pool_instances = 1
innodb_log_buffer_size = 64M
And the Percona version I'm running:
mysqld --version
Ver 8.0.15-6 for debian-linux-gnu on x86_64 (Percona Server (GPL), Release '6', Revision '63abd08')
OS: Ubuntu 18.04.2 LTS
Hardware:
CPU: Intel(R) Xeon(R) Platinum 8175M CPU # 2.50GHz
RAM: 32G
The queries I'm running are all based on unique indexes (no joins), tables are all InnoDB. The same configuration worked fine until the update to Percona 8.
The my.cnf settings I had to remove after the upgrade as they were no longer supported are:
innodb_locks_unsafe_for_binlog = 0
query_cache_size = 0
query_cache_type = 0
Things I tried:
I ran mysqltuner.pl but didn't get any relevant advice from it.
ulimit -n and ulimit -s show values significantly higher than what I'm using (1048576 and 16384 specifically).
Any other suggestions?
Related
[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_general_ci
innodb_file_per_table=ON
innodb_buffer_pool_size = 8G
aria_pagecache_buffer_size = 2000M
max_connections = 150
max_allowed_packet=500M
tmp_table_size = 64M (was 16M before)
slow_query_log = 1
long_query_time = 1
slow_query_log_file = /var/log/mariadb/slow-query.log
I have 20GB of RAM, and Raid HDD on my Centos server. I have php-fpm, nginx and mariadb configuration. When I reboot mariadb service the system is stable and MYSQL consumes about 30% of CPU according to TOP. During some hours memory consuming is growing but not really quickly. But over time, when MYSQL starts consuming 10GB of RAM it starts over-loading CPU to about 500%. In process list I typically see a lot of slow connections.
How can I tune the database?
I have MAMP Pro on El Capitan running. It has been fine up until now, but I've run into a problem. I have a mixture of database, some using the MyISAM Engine and others using InnoDB. I don't really know how that works. I guess if some are InnoDB, the Engine is still MyISAM by default. The issue is with databases that I have for Atlassians Confluence and JIRA. In Confluence, all is good, but it says:
You should increase innodb_log_file_size to 256M
I tried playing around with the my.cnf, but ran into issues. I restored things, and these are the relevant sections from the config.
[mysqld]
#port = 9999
socket = /Applications/MAMP/tmp/mysql/mysql.sock
key_buffer_size = 64M
max_allowed_packet = 512M
# table_cache only works for MySQL 5.5.x
#table_cache = 64
# If you are running MySQL 5.6.x, use table_open_cache.
#table_open_cache = 64
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 32M
#Uncomment the following if you are using InnoDB tables
#innodb_data_home_dir = /Applications/MAMP/db/mysql/
#innodb_data_file_path = ibdata1:10M:autoextend
#innodb_log_group_home_dir = /Applications/MAMP/db/mysql/
# You can set .._buffer_pool_size up to 50 - 80 %
# of RAM but beware of setting memory usage too high
#innodb_buffer_pool_size = 128M
#innodb_additional_mem_pool_size = 2M
# Set .._log_file_size to 25 % of buffer pool size
#innodb_log_file_size = 512M
#innodb_log_buffer_size = 8M
#innodb_flush_log_at_trx_commit = 1
#innodb_lock_wait_timeout = 50
When I uncommented the InnoDB section the server crashes and the database got corrupted.
Just wondering how I can turn on InnoDB for MAMP, if that is recommended, and update my existing databases at the same time, the MyISAM ones and the InnoDB ones.
While I'm at it, I might want to upgrade MAMP to the newer MySQL version, maybe later.
How much RAM do you have?
Keep max_allowed_packet under 2% of RAM.
Since you are using both MyISAM and InnoDB, set innodb_buffer_pool_size to about 1/3 of RAM unless; less if you have a tiny system.
Do not change innodb_log_file_size without further instructions. That is, don't set it in my.cnf if it is not already set.
MyISAM and InnoDB can coexist.
I am on linux box running only mysql with 8 cores and 16GB ram. All connections come from web server on another machine in the same network running php with codeigniter.
I cannot get more than 150 connections on mysql.
My my.cnf is:
[mysqld]
user=mysql
port = 3306
socket = /tmp/mysql.sock
datadir = /usr/local/mysql/var/
skip-external-locking
max_connections=500
max_user_connections=500
open-files-limit = 500
key_buffer_size = 2048M
max_allowed_packet = 32M
table_open_cache = 512
sort_buffer_size = 2M
read_buffer_size = 2M
read_rnd_buffer_size = 16M
myisam_sort_buffer_size = 128M
thread_cache_size = 250
table_definition_cache = 1024
query_cache_size = 32M
query_cache_limit = 32M
table_cache=1024
max_heap_table_size=1024M
key_buffer=2048M
wait_timeout=60
thread_concurrency = 16
long_query_time = 1
tmp_table_size=256M
show status returns that max_connections and max_user_connections to be 500.
Since mysql is saying that connection limit is 500, I thought there are other setting in PHP, apache or codeigniter that is limiting the requests to mysql, but I cannot find any. I've searched google for few days trying to find answers without any luck.
Are there limits set on any of the above mentioned software? I will post configs if necessary.
Thank you.
Check the Max number of Apache worker processes (ServerLimit and MaxClients) in httpd.conf. Assuming a fixed number of connections per worker, you might be maxing out your number of workers, so nothing is requesting new MySQL connections.
Sorry, just found this on Google, but your config is foobar
max_connections=500
open-files-limit = 500
table_open_cache = 512
table_definition_cache = 1024
open-files-limit: 500 #; not good!
table_open_cache: 512... * 2+ open-files per table = 1024 open-files used minimum
max_connections: 500 each open connection starts a new file handle to buffer.
Your mysql will open some 130 tables just to start (core tables) which leaves you with a mere 240 file handles to share between data queries and connections. For each connection with a table query, 3+ file handles are consumed (connection, data table, index file(s)). That maxes your open-files long before you get 150 connections. open-files-limit needs to start >2048 for that kind of DB usage.
more help:
show global status like '%open%';
show global status like '%onnect%';
see for yourself how many files/connections are actually in use. some operating systems (Windows XP) hard limit files/network connections. try googling "mysql 'YOUR-OS' 150 connections" and see if that is the limiting factor.
I have a Xeon 2.0Ghz server (12 cores) with 16GB memory, running Apache and mySQL for a website with around 50,000 records in InnoDB (Percona). My queries used to return in about 0.17 to 0.25 seconds, then I ran the Percona tools mySQL optimizer, uploaded the new my.cnf file and suddenly the same queries are taking 1.20 to 1.30 seconds, so about 5x longer.
What did I do wrong? Here are my old and new my.cnf files"
NEW:
[mysqld]
default_storage_engine = InnoDB
key_buffer_size = 32M
myisam_recover = FORCE,BACKUP
max_allowed_packet = 16M
max_connect_errors = 1000000
log_bin = /var/lib/mysql/mysql-bin
expire_logs_days = 14
sync_binlog = 1
tmp_table_size = 32M
max_heap_table_size = 32M
query_cache_type = 0
query_cache_size = 0
max_connections = 200
thread_cache_size = 50
open_files_limit = 65535
table_definition_cache = 1024
table_open_cache = 2048
innodb_flush_method = O_DIRECT
innodb_log_files_in_group = 2
innodb_log_file_size = 256M
innodb_flush_log_at_trx_commit = 1
innodb_file_per_table = 1
innodb_buffer_pool_size = 12G
log_error = /var/lib/mysql/mysql-error.log
log_queries_not_using_indexes = 1
slow_query_log = 1
slow_query_log_file = /var/lib/mysql/mysql-slow.log
OLD:
[mysqld]
innodb_buffer_pool_size = 12000M
innodb_log_file_size = 256M
innodb_flush_method = O_DIRECT
innodb_file_per_table = 1
innodb_flush_log_at_trx_commit = 2
innodb_log_buffer_size = 16M
innodb_additional_mem_pool_size = 20M
innodb_thread_concurrency = 20
read_rnd_buffer_size=50M
query_cache_size=128M
query_cache_type=1
tmp_table_size=512M
wait_timeout=90
query_cache_limit=64M
key_buffer_size=128M
max_heap_table_size=512M
max_allowed_packet=32M
log_slow_queries
log-queries-not-using-indexes
long_query_time = 1
Are you swapping at all after running for a while?
You might try turning down your innodb_buffer_pool_size since you say the server is also running Apache. At the moment it looks like MySQL has the potential to use up all the server's memory for itself and leave nothing for the OS and Apache.
Try setting innodb_buffer_pool_size to 8G and then set innodb_log_file_size to 2G.
You can probably up your innodb_thread_concurrency as well, but since it isn't a dedicated MySQL server it may be fine at the default of 8. It depends on what CPU you have but the docs say:
The correct value for this variable is dependent on environment and
workload. You will need to try a range of different values to
determine what value works for your applications. A recommended value
is 2 times the number of CPUs plus the number of disks.
So play around with that and see what works best.
Also, is your database larger than the amount of RAM you have or could your entire DB fit in memory?
Just keep in mind that since you are running Apache on the same server, Apache is going to want to create a bunch of its own threads and consume as much memory as required for all the server processes and if you're running something like PHP that's going to take up memory as well.
You're going to have to find a good balance where both Apache and MySQL can both perform at maximum capacity on the same system but where neither one uses so much memory that the other has to swap.
Additional ways you can troubleshoot or profile performance would be to check your slow query log and run explains on the slow queries. In addition, you can install the Percona toolkit and run pt-query-digest to analyze your performance. Read the docs here.
Currently I have 3 servers running, 2 remote, Main server running MySQL 5.5.24 and backup running MySQL 5.1.63 and 1 local running MySQL 5.5.20 for development. The main server is used for reporting purposes; currently have 144 tables (MyISAM and InnoDB), and about 80gb of data, the larger tables have about 13 million rows each one.
On the remote servers I have very limited access through webmin, because of this I can’t make the changes directly, I need to ask to IT department for them.
I’m having some serious performance issues on the Main server since a MySQL crash we had last month. The server was running a development release which had some disk writing bugs, after the recovery we installed the MySQL 5.5.23 version and that’s when the performance issues began. We recently installed MySQL 5.5.24 (lastest stable version) but we still have the performance issues
Here are the servers configurations, all are dedicated servers:
Main:
Operating system: Gentoo Linux
Kernel and CPU: Linux 2.6.31-gentoo-r6 on x86_64
Processor information: Intel(R) Xeon(TM) CPU 2.66GHz, 8 cores
Real memory (ram): 23.55 GB total
Virtual memory: 3.74 GB total
Local disk space: 463.38 GB total (about 30% free)
Backup:
Operating system: Gentoo Linux
Kernel and CPU: Linux 2.6.31-gentoo-r6 on x86_64
Processor information: Intel(R) Core(TM)2 Duo CPU E6405 # 2.13GHz, 2 cores
Real memory (ram): 15.68 GB total
Virtual memory: 16.01 GB total
Local disk space: 4.73 TB total (about 80% free)
Development:
Operating system: Ubuntu Linux 9.04
Kernel and CPU: Linux 2.6.32-33-server on x86_64
Processor information: Intel(R) Core(TM)2 Duo CPU E6550 # 2.33GHz, 2 cores
Real memory (ram): 1.95 GB total
Virtual memory: 5.65 GB total
Local disk space: 141.15 GB total (about 5% free)
All the servers have the same my.cnf configuration, except for the innodb_buffer_pool_size
my.cnf
[mysqld]
back_log = 50
max_connections = 100
max_connect_errors = 10
table_open_cache = 2048
max_allowed_packet = 16M
binlog_cache_size = 1M
max_heap_table_size = 64M
read_buffer_size = 2M
read_rnd_buffer_size = 16M
sort_buffer_size = 8M
join_buffer_size = 8M
thread_cache_size = 8
thread_concurrency = 8
query_cache_size = 64M
query_cache_limit = 2M
ft_min_word_len = 4
default-storage-engine = MYISAM
thread_stack = 262K
stored_program_cache= 1024
transaction_isolation = REPEATABLE-READ
tmp_table_size = 64M
binlog_format=mixed
slow_query_log
long_query_time = 2
key_buffer_size = 512M
bulk_insert_buffer_size = 64M
myisam_sort_buffer_size = 128M
myisam_max_sort_file_size = 10G
myisam_repair_threads = 1
myisam_recover
innodb_additional_mem_pool_size = 16M
innodb_buffer_pool_size = 8G
innodb_data_file_path = ibdata1:10M:autoextend
innodb_write_io_threads = 8
innodb_read_io_threads = 8
innodb_thread_concurrency = 16
innodb_flush_log_at_trx_commit = 1
innodb_log_buffer_size = 8M
innodb_log_file_size = 256M
innodb_log_files_in_group = 3
innodb_max_dirty_pages_pct = 90
innodb_lock_wait_timeout = 240
server-id = 1
event_scheduler = 1
[mysqldump]
quick
max_allowed_packet = 16M
[mysql]
no-auto-rehash
[myisamchk]
key_buffer_size = 512M
sort_buffer_size = 512M
read_buffer = 8M
write_buffer = 8M
[mysqlhotcopy]
interactive-timeout
[mysqld_safe]
open-files-limit = 8192
I’ve tried several large Stored Procedures with lots of columns and data and the backup server is about 10x faster than the main server, and running them on development server its about 5x faster than main.
Since the main server and the backup server are on the same remote location and through a VPN I know there are no connection speed issues.
I can’t post the Stored Procedures code, but I know the issue is on the final SELECT since the creation of all temporary tables are pretty fast, and I can see in the MySQL monitor (using SHOW FULL PROCESSLIST) that the SELECT is taking 95% of the time. Most of the Stored Procedures works with tons of data, with multiples joins.
Any Ideas why the main server could be having so bad performance even it’s the most powerful?
We've been looking for reported performance bugs of the latest versions, but what we found didn't help at all http://bugs.mysql.com/bug.php?id=44585
I'll really appreciate any help
Would this question better be asked on server fault? It's my first question
Sorry about my english.
Are the same tables involved in all of the problematic SELECT statements in the Stored Procedures you tried? Perhaps the index statistics need to be rebuilt on some of them - check out the OPTIMIZE TABLE command.
Finally we moved the DB to another server, new version of MySQL