Hi Bruno, The 'db' is pretty much the first model to be defined, and never ever reset, and all of them in root.
And note that 'db' is just one specific example of the many other errors I could get during concurrency. For reference, objects instantiated in the first model suddenly are NOT recognized global in subsequent models / controller, same as what occurred with 'db'. And this occurs only during concurrency, i.e. everything works perfectly fine during non-concurrent web requests. Remember that my models code (so much more than db definitions) are huge (which is not the point for this issue). Thanks again, Carlos