Access violation during obstacle processing #15494
Description
Dear colleagues!
Starting with FDS version 6.10.1, we've occasionally encountered problems when running simulations.
Sometimes a message like the following appears:
forrtl: severe (157): Program Exception - access violation
Initialization of symbol handler failed. Error code %d:3221225477
Sometimes the program closes without any messages.
The problem occurs occasionally, and only when processing relatively large files with a large number of obstacles. Often the problem can be circumvented by changing the size of one of the obstacles, or by changing the size of the MESH.
Finally, we were able to look at this issue in more detail. Through trial and error, we were able to significantly reduce the number of obstacles in one of our real projects so that the error still remained. The remaining number of obstacles is slightly more than a hundred. All obstacles have coordinates and sizes that are multiples of the cell size of the computational domain.
The project contains only OBSTs. The source of the fire can be removed, but the error will remain. It is interesting and important to note that the error will disappear if you remove almost any obstacle from the project. For example, you can remove just the first, or second, or third, or tenth, or last obstacle, and the simulation will run successfully. I'm not sure this applies to every single obstacle. However, we spent a lot of time manually removing obstacles that don't affect the results. The attached file contains a minimal, or near-minimal, example that reproduces the problem.
The lines between the OBST declarations are object identifiers for our program. I assume they have no effect.
The issue occurs in FDS versions 6.10.1 and the nightly build. The issue does not occur in version 6.9.1.
We run Windows 10.