Codeigniter数据库会话GET LOCK

Question

I have two webservers running Codeigniter framework and use a load balancer, and I want to store the shared session for both webservers instead of using sticky session from load balancer.

I tried to use ci database session. For few days the connections were excellent, until suddenly it start showing slow query like this:

SELECT GET_LOCK('59e30181bfafeae2d31394d621bab3cc4c401956', 300) AS ci_session_lock;

The query can take from 5 - 15 seconds which slow down the servers.

This is the session configuration in config.php

$config['sess_driver'] = 'database';
$config['sess_cookie_name'] = 'ci_session';
$config['sess_expiration'] = 0; //expire when the browser is closed 
$config['sess_save_path'] = 'ci_sessions';
$config['sess_match_ip'] = FALSE;
$config['sess_time_to_update'] = 300;
$config['sess_regenerate_destroy'] = FALSE;

Does anyone ever experience like this? Thanks before.

Answer 1

If you are facing slow query issue then you need to save your session into files instead of database, this will save your slow and multiple query request.

Example:

$config['sess_driver'] = 'files'; // need to use files

The storage driver to use in CI: files, database, redis, memcached

Then define tmp path:

$config['sess_save_path'] = sys_get_temp_dir();

According to PHP manual, sys_get_temp_dir() Returns directory path used for temporary files

You can also set specific folder to save session in $config['sess_save_path'] as:

$config['sess_save_path'] = 'session_folder'; // this will save session on root inside **session_folder** folder.