Tickets :: Comment on [#9173] Deadlocks in mysql SessionHandler under heavy loads

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Comment	> We use the mysql Sessionhandler of Horde on our installation, and > under heavy loads (> 500 users), we start having a lot of deadlocks > messages in the logs: > > Aug 05 09:45:47 HORDE [error] [horde] Error writing session data: > Deadlock found when trying to get lock; try restarting transaction > [pid 27607 on line 185 of > "/htdocs/horde/lib/Horde/SessionHandler/mysql.php"] > > When this happens, users have to try to login many times before > getting access. > > We added the following statement to the mysql driver and it solved > the problem nicely: > > mysql_query('SET TRANSACTION ISOLATION LEVEL READ COMMITTED;', $this->_db); > > ref: http://dev.mysql.com/doc/refman/5.0/en/set-transaction.html > > No more deadlock seen even for > 2000 active users
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