{"action":"created","issue":{"url":"https://api.github.com/repos/colinmollenhour/Cm_RedisSession/issues/50","labels_url":"https://api.github.com/repos/colinmollenhour/Cm_RedisSession/issues/50/labels{/name}","comments_url":"https://api.github.com/repos/colinmollenhour/Cm_RedisSession/issues/50/comments","events_url":"https://api.github.com/repos/colinmollenhour/Cm_RedisSession/issues/50/events","html_url":"https://github.com/colinmollenhour/Cm_RedisSession/issues/50","id":46441383,"number":50,"title":"frequent read error on connection in backend only","user":{"login":"jonathanvaughn","id":1672327,"avatar_url":"https://avatars.githubusercontent.com/u/1672327?v=3","gravatar_id":"","url":"https://api.github.com/users/jonathanvaughn","html_url":"https://github.com/jonathanvaughn","followers_url":"https://api.github.com/users/jonathanvaughn/followers","following_url":"https://api.github.com/users/jonathanvaughn/following{/other_user}","gists_url":"https://api.github.com/users/jonathanvaughn/gists{/gist_id}","starred_url":"https://api.github.com/users/jonathanvaughn/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/jonathanvaughn/subscriptions","organizations_url":"https://api.github.com/users/jonathanvaughn/orgs","repos_url":"https://api.github.com/users/jonathanvaughn/repos","events_url":"https://api.github.com/users/jonathanvaughn/events{/privacy}","received_events_url":"https://api.github.com/users/jonathanvaughn/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":14,"created_at":"2014-10-21T20:35:16Z","updated_at":"2015-01-26T10:14:41Z","closed_at":null,"body":"We are having repeated problems with the admin backend in Magento, but not any frequent problems on the front end. The front end is handled on two separate nodes, and a third runs the backend, all sharing common Redis caches (separate instances for Sessions, Magento Cache, and Full Page Cache). The Redis instances are on a 4th server.\r\n\r\n```\r\na:5:{i:0;s:71:\"read error on connection\";i:1;s:2311:\"#0 /var/www/vhosts/www.example.com/.modman/Cm_RedisSession/code/Model/Session.php(380): Credis_Client->__call('exec', Array)\r\n#1 /var/www/vhosts/www.example.com/.modman/Cm_RedisSession/code/Model/Session.php(380): Credis_Client->exec()\r\n#2 [internal function]: Cm_RedisSession_Model_Session->read('cm0uenj0pdj4im6...')\r\n#3 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Model/Session/Abstract/Varien.php(125): session_start()\r\n#4 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Model/Session/Abstract/Varien.php(168): Mage_Core_Model_Session_Abstract_Varien->start('adminhtml')\r\n#5 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Model/Session/Abstract.php(84): Mage_Core_Model_Session_Abstract_Varien->init('core', 'adminhtml')\r\n#6 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Model/Session.php(42): Mage_Core_Model_Session_Abstract->init('core', 'adminhtml')\r\n#7 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Model/Config.php(1348): Mage_Core_Model_Session->__construct(Array)\r\n#8 /var/www/vhosts/www.example.com/app/Mage.php(463): Mage_Core_Model_Config->getModelInstance('core/session', Array)\r\n#9 /var/www/vhosts/www.example.com/app/Mage.php(477): Mage::getModel('core/session', Array)\r\n#10 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Controller/Varien/Action.php(493): Mage::getSingleton('core/session', Array)\r\n#11 /var/www/vhosts/www.example.com/app/code/core/Mage/Adminhtml/Controller/Action.php(160): Mage_Core_Controller_Varien_Action->preDispatch()\r\n#12 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Controller/Varien/Action.php(407): Mage_Adminhtml_Controller_Action->preDispatch()\r\n#13 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('start')\r\n#14 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))\r\n#15 /var/www/vhosts/www.example.com/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()\r\n#16 /var/www/vhosts/www.example.com/app/Mage.php(684): Mage_Core_Model_App->run(Array)\r\n#17 /var/www/vhosts/www.example.com/index.php(98): Mage::run('', 'store')\r\n#18 {main}\";s:3:\"url\";s:99:\"/index.php/admin/sales_order_create/start/customer_id/3115/key/99f5680349b18f208dc386bcceaec7a6/\";s:11:\"script_name\";s:10:\"/index.php\";s:4:\"skin\";s:5:\"admin\";}\r\n```\r\n\r\nThere isn't a large number of admin requests occurring (typically only one or two people using it) and the other nodes appear to communicate to Redis just fine. They're all Rackspace cloud performance 8GB servers in the same DC.\r\n\r\nSince this only happens in the backend, I'm not sure if it's just a backend triggered issue, or if it's the server, but I've tried monitoring connectivity to redis from that server and it never fails (and the cache / full page cache never error, just sessions).\r\n\r\nAny suggestions on what to look for / instrument to investigate this? I tried adding a call to a shell command to get the number of active / time_wait / etc Redis connections when the error occurs, but there's never more than a couple in total on that server, so I'm pretty sure its not any kind of socket/descriptor starvation.\r\n\r\nedit: replaced stacktrace with correct one"},"comment":{"url":"https://api.github.com/repos/colinmollenhour/Cm_RedisSession/issues/comments/71439036","html_url":"https://github.com/colinmollenhour/Cm_RedisSession/issues/50#issuecomment-71439036","issue_url":"https://api.github.com/repos/colinmollenhour/Cm_RedisSession/issues/50","id":71439036,"user":{"login":"seansan","id":652395,"avatar_url":"https://avatars.githubusercontent.com/u/652395?v=3","gravatar_id":"","url":"https://api.github.com/users/seansan","html_url":"https://github.com/seansan","followers_url":"https://api.github.com/users/seansan/followers","following_url":"https://api.github.com/users/seansan/following{/other_user}","gists_url":"https://api.github.com/users/seansan/gists{/gist_id}","starred_url":"https://api.github.com/users/seansan/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/seansan/subscriptions","organizations_url":"https://api.github.com/users/seansan/orgs","repos_url":"https://api.github.com/users/seansan/repos","events_url":"https://api.github.com/users/seansan/events{/privacy}","received_events_url":"https://api.github.com/users/seansan/received_events","type":"User","site_admin":false},"created_at":"2015-01-26T10:14:41Z","updated_at":"2015-01-26T10:14:41Z","body":"@colinmollenhour is there maybe a way to debug all calls and replies from REDIS? Maybe this way I can help to debug this issue /// see what is going on"}}