How does AE handle this,
It doesn't, since it doesn't have to - normally. Such files should be locked by the server software and/or be duplicated via a virtual file system to provide each user with its own instance. Obviously in your case that doesn't work. Either because it's a cheap NAS with limited abilities or generally your user management having a lot of loose ends and loopholes and the server not being able to figure out who is who.... Take a pick! Anyway, definitely outside AE's sphere of influence and you need to spend some time straigthetning out the more fundamental issues in question here...
What if two instances of AE are running on the same workstation? So forget my example I specified above. You just have two instances of AE running accessing the same footage file.
I'm curious if anybody has happened across this situation before. That is, you load up two instances of AE on a Windows machine using the -m flag on the command line. Then, in each of the instances, open two different AEP files that access the same footage file.
In my case, under this scenario, under one logged in user running the instances, AE will deliver an error saying
After Effects error: Error(4) reading frame from file "common.mov"
Is this just not possible? It seems like it should since, with aerender, you can obviously run multiple project files which access the same footage file.
Does afterfx.exe just not work that way? I see that aerender actually launches AfterFX.com which is different than afterfx.exe.
Anyways, does anybody know how to successfully load up two instances of AE using the -m flag, and open two different project files that access the same footage resource?