SQLSTATE[HY000] [1040] Too many connections

[jason_long]

Hello,

Sometime when I want to browse my website, the "SQLSTATE[HY000] [1040] Too many connections" error appeared.

Trace:
#0 /srv/MyWebsite/public/lib/Zend/Db/Adapter/Pdo/Mysql.php(111): Zend_Db_Adapter_Pdo_Abstract->_connect()
#1 /srv/MyWebsite/public/lib/Varien/Db/Adapter/Pdo/Mysql.php(396): Zend_Db_Adapter_Pdo_Mysql->_connect()
#2 /srv/MyWebsite/public/lib/Zend/Db/Adapter/Abstract.php(460): Varien_Db_Adapter_Pdo_Mysql->_connect()
#3 /srv/MyWebsite/public/lib/Zend/Db/Adapter/Pdo/Abstract.php(238): Zend_Db_Adapter_Abstract->query('SET NAMES utf8', Array)
#4 /srv/MyWebsite/public/lib/Varien/Db/Adapter/Pdo/Mysql.php(504): Zend_Db_Adapter_Pdo_Abstract->query('SET NAMES utf8', Array)
#5 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource.php(179): Varien_Db_Adapter_Pdo_Mysql->query('SET NAMES utf8')
#6 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource.php(110): Mage_Core_Model_Resource->_newConnection('pdo_mysql', Object(Mage_Core_Model_Config_Element))
#7 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource/Db/Abstract.php(320): Mage_Core_Model_Resource->getConnection('core_write')
#8 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource/Db/Abstract.php(350): Mage_Core_Model_Resource_Db_Abstract->_getConnection('write')
#9 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource/Db/Abstract.php(335): Mage_Core_Model_Resource_Db_Abstract->_getWriteAdapter()
#10 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource/Db/Abstract.php(360): Mage_Core_Model_Resource_Db_Abstract->_getReadAdapter()
#11 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Resource/Db/Collection/Abstract.php(134): Mage_Core_Model_Resource_Db_Abstract->getReadConnection()
#12 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Config.php(1348): Mage_Core_Model_Resource_Db_Collection_Abstract->__construct(Object(Mage_Core_Model_Resource_Website))
#13 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Config.php(1380): Mage_Core_Model_Config->getModelInstance('core_resource/w...', Object(Mage_Core_Model_Resource_Website))
#14 /srv/MyWebsite/public/app/Mage.php(491): Mage_Core_Model_Config->getResourceModelInstance('core/website_co...', Object(Mage_Core_Model_Resource_Website))
#15 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Abstract.php(208): Mage::getResourceModel('core/website_co...', Object(Mage_Core_Model_Resource_Website))
#16 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/Abstract.php(213): Mage_Core_Model_Abstract->getResourceCollection()
#17 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/App.php(619): Mage_Core_Model_Abstract->getCollection()
#18 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/App.php(477): Mage_Core_Model_App->_initStores()
#19 /srv/MyWebsite/public/app/code/core/Mage/Core/Model/App.php(360): Mage_Core_Model_App->_initCurrentStore('', 'store')
#20 /srv/MyWebsite/public/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#21 /srv/MyWebsite/public/index.php(82): Mage::run('', 'store')
#22 {main}

The MySQL config is:

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
skip-show-database

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

# Settings user and group are ignored when systemd is used (fedora >= 15).
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mysqld according to the
# instructions in http://fedoraproject.org/wiki/Systemd
user=mysql

# Semisynchronous Replication
# http://dev.mysql.com/doc/refman/5.5/en/replication-semisync.html
# uncomment next line on MASTER
;plugin-load=rpl_semi_sync_master=semisync_master.so
# uncomment next line on SLAVE
;plugin-load=rpl_semi_sync_slave=semisync_slave.so

# Others options for Semisynchronous Replication
;rpl_semi_sync_master_enabled=1
;rpl_semi_sync_master_timeout=10
;rpl_semi_sync_slave_enabled=1

# http://dev.mysql.com/doc/refman/5.5/en/performance-schema.html
;performance_schema


[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid


#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

bind-address = 127.0.0.1
local-infile=0

What is my problem?

Please look at:

https://pasteboard.co/IGjzewW.png 

The memory is full

Thanks.

[Vimal Kumar]

Hi @jason_long,

You need to increase the memory limit on the server.

For the quick fix, just restart the server and mysql.

I hope it will help you!

[jason_long]

Restart the server? It is not a good idea. How can I troubleshoot it?

[Vimal Kumar]

Hi @jason_long,

check the below stack link.
https://stackoverflow.com/a/24225501

I hope it will help you!

[jason_long]

Is "max_connections" mandatory?

[Vimal Kumar]

I think yes, because there is already a default value for max connection on server level.

[Mukesh Tiwari]

Hi @jason_long 

Please run following command in MySql 

show variables like 'max_connections';

It will show maximum connections allowed at a time. 
Based on your requirement you can update the value.

In your MySql's my.cnf file you can set the desired value.

For example to set 200 value
max_connections = 200

Please refer following articles which will help you.
https://dev.mysql.com/doc/refman/5.5/en/too-many-connections.html

https://www.percona.com/blog/2013/11/28/mysql-error-too-many-connections/