4D Server v11.4 Crash

[rjsharp]

Greetings.

We’ve recently upgraded a large web-based 4D Server app to v11.4 HF3 (Windows Server 2003).

Twice this week, 4D Server has crashed, and according to Windows the responsible module was "NT_Auth".

Based on web access logs, I suspect there’s a problem when two users login at the same moment, i.e. two processes using NTLogon at the same time. In the 4D 2003 version of this app we didn’t surround the call to NT_Auth with a semaphore. Do you recommend that we use one? Have you heard of any other crashing problems with NTLogon and 4D v11?

Thanks,

RJ

[mylesw]

You are the first to report this, but that's not to say others are not experiencing it.

4D has an AWFUL way of handling concurrent threading for Plug-ins and our code does not do anything to attempt to run in its own threading model. Since the plug-in simply calls the Windows network libraries to do the login on behalf of the users who request it, it would not surprise me that 4D may be having issues with concurrency. I cannot comment regarding v11 as we do not develop in it, and don't have any clients running it with NTLogon. But if they were to have changed the threading support for plugins (something dearly needed IMHO), then it is highly possible that a bug in 4D Server or a change in the expectation as to how the calls are made to plugins would cause NTLogon some grief.

My advice would be to setup some form of semaphore handling so that you can guarantee that only one user at a time can call this. I'm sure its not a problem within Windows, as I would not expect multiple logins to cause any issue with the natural threading of Windows for this. But 4D Server would be the likely culprit and protecting yourself from any dysfunction that it may have for multiple concurrent calls to NTLogon would be highly advisable if you are running a high demand, enterprise application.

Myles
_________________
Myles Wakeham
Director of Engineering
Tech Solutions, USA Inc.
myles@techsol.org