It's always a pleasure to uncover shared memory problems when working with base vi.lib methods that *should* work as preallocated clones and have uninitialized shift registers and then having to establish a chain of vi references to safely call those methods in an application with distributed/parallel threads. It feels like extra work but does fix the problem. It's a major unknown gotcha unless you're already familiar with the vi you are calling.
My most recent hiccup: the NI PID library. I needed two closed loop controllers in actor framework, and was getting very strange timing, setpoint, process variable, and control output crossovers until I realized the stock .vi's had shared memory in the form of uninitialized shift registers (despite being in the context of a pre-allocated actor). Creating references of the vi's I needed and storing them in the actor at launch fixed the problem, but at that point the effort in writing my own PID .vi starts to be a favorable time tradeoff. At least I am able to peek under the hood of the PID library, other aspects of vi.lib... not so much.
Or maybe this is a teaching problem. I haven't come across ways of navigating this issue from official NI documentation, in fact the way I learned I needed to call the PID.vi by-reference was from the forum and rather matter-of-factly. There are a couple of great blogs that cover this issue in detail, so I don't feel alone in my ignorance. Maintaining State Information in LabVIEW Applications, Part 5 - LabVIEW Field Journal Archives | Lab...
