Extremely irritating board bug, please advise

nikdom · 12-27-2012, 08:44 AM

I think I know what the issue is.

It's not the checking the 'Remember Me' check box. All that does is create a cookie on the user's browser. If my guess is correct, the problem is on the server side.

More than likely TW is using multiple servers for hosting the vBulletin PHP application that powers these boards. These servers are usually placed behind what's called a load-balancer :- meaning that incoming HTTP requests are routed to one or more servers. When a login request goes to a server, that individual server creates what's called a "Session" (a server side cookie) for that user ON THAT server. These "sessions" are usually not transferred between the different servers (unless TW does something more complicated called session-replication in which case the replication is slow)

You can see right away what the problem is then. Server A logs you in and creates a session on that server and redirects your browser to the next page. Unfortunately, if the load balancer is not doing what's called a "sticky session", i.e sticking your requests to that one server, this redirect request goes to another server B behind the same load balancer. Server B has no clue you have logged in (since it has no session for you) and asks that you log in again. This process can repeat if there are multiple servers and the load balancer is not doing sticky sessions.

The reason I think the load balancer is the problem is because you can confirm it by doing this -

1. Enter your login information and hit enter
2. Now you're back to a page where you're asked again for your login information or you are on one of the forum pages but it does not show you as logged in at the top.
3. Now keep refreshing the forum page. Eventually you'll find that it shows you as logged in.

What's happened is by refreshing you're sending multiple requests for the page and eventually the balancer sent one to one of the servers which DOES have a session for you.

I'm happy to offer any assistance if one of the mods wants to contact me. You would need to get in touch with your hosting/IT staff and have them resolve the round-robin load balancer issue with sticky sessions.

tl;dr version -

- Refresh the page (or keep doing so) until you see you're logged in.
- Problem is a technical one on the Warehouse servers which is not debilitating but most likely the one described in detail above

12-27-2012, 08:44 AM	#21
nikdom Hall Of Fame Join Date: Mar 2009 Location: Tennisville Posts: 4,468	I think I know what the issue is. It's not the checking the 'Remember Me' check box. All that does is create a cookie on the user's browser. If my guess is correct, the problem is on the server side. More than likely TW is using multiple servers for hosting the vBulletin PHP application that powers these boards. These servers are usually placed behind what's called a load-balancer :- meaning that incoming HTTP requests are routed to one or more servers. When a login request goes to a server, that individual server creates what's called a "Session" (a server side cookie) for that user ON THAT server. These "sessions" are usually not transferred between the different servers (unless TW does something more complicated called session-replication in which case the replication is slow) You can see right away what the problem is then. Server A logs you in and creates a session on that server and redirects your browser to the next page. Unfortunately, if the load balancer is not doing what's called a "sticky session", i.e sticking your requests to that one server, this redirect request goes to another server B behind the same load balancer. Server B has no clue you have logged in (since it has no session for you) and asks that you log in again. This process can repeat if there are multiple servers and the load balancer is not doing sticky sessions. The reason I think the load balancer is the problem is because you can confirm it by doing this - 1. Enter your login information and hit enter 2. Now you're back to a page where you're asked again for your login information or you are on one of the forum pages but it does not show you as logged in at the top. 3. Now keep refreshing the forum page. Eventually you'll find that it shows you as logged in. What's happened is by refreshing you're sending multiple requests for the page and eventually the balancer sent one to one of the servers which DOES have a session for you. I'm happy to offer any assistance if one of the mods wants to contact me. You would need to get in touch with your hosting/IT staff and have them resolve the round-robin load balancer issue with sticky sessions. tl;dr version - - Refresh the page (or keep doing so) until you see you're logged in. - Problem is a technical one on the Warehouse servers which is not debilitating but most likely the one described in detail above Last edited by nikdom : 01-06-2013 at 11:18 AM.

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