I have a PHP script that will store session hash in the database for each client (who's online table). I don't know why, but recently I noticed almost all clients have multiple session ids. I don't remember changing the configuration of the server. Also, some clients like myself only have 1 session id, which is weird...
Since, almost each clients have multiple sessions, multiple session files are also created on the server. And every time they navigate to another page, which by the way will update their activity by executing an SQL query, the query is also executed multiple times for each session ids they have. And now the server is constantly getting a high CPU load and excessive memory usage.
Can someone tell me what's wrong? I have a CentOS VPS (5.5 x64)