I've got a sim that when I increase the res, at a certain, seemingly arbitrary frame, it'll go from ~30 seconds per frame, to getting hung up on something, and even after 5+ hours, it never makes it to the next frame... but there's no error - it just continues forever using a single CPU core, and I can't even work out a way to meaningfully pin down what node is causing it.

Is there any way to put in Error nodes that trip when their input takes beyond a certain time to cook? Nothing in the scene should take longer than a 10-15 seconds, so if I could get it to throw a debug message when something upstream has taken longer than say, 5 minutes, I might be able to actually track down what's causing it.

Well, narrowed it down in the end, by putting "printf" vex detail-wrangles into SOP Solvers, and spamming them after every DOP node. Pinned it down to the pressure field advection step near the end of the FLIP solver, that's used for the Warm-Start Solver option. Luckily that's pretty optional, so I just turned it off for now.

...No time to try and work out *why* the Gas Advect Field DOP would be stalling out indefinitely like that. Seems like that should be a pretty well-debugged core node after all these years - perhaps I'm introducing some rogue velocities into the sim somehow, and it's messing with the pressure solve.