Autosweeper frequently kind of works (not)...

Would it be possible for you also provide a copy of the save as close to this one as possible but from the release branch of the game (not the beta)?

@HarryMcCleave:

Sure thing.

This is save 527 on cycle 17630, I can confirm that loading this older save in the preview branch has the errant behavior. 

Important: I was experimenting with keeping some duplicants inside tourist sight-seeing modules. This causes a game crash if you click on any doors. 

Do not click on any doors. 

If you want to click on doors then you have to release all the duplicants that are inside the rocket into the wild so that door permissions don't summon a black hole.

 

The hydro sensor at the bottom of the build sets the whole contraption in motion, just toggle it once to set the memory toggle that keeps the salt water flowing:

I also have older saves.

 

DeCrew 527.sav

@HarryMcCleave:
Asked the modding community on Discord for details on the targeting/scanning algorithm for autosweepers. TL;DR: They start at their bottom left corner and continue right then scan the next row upwards.

With this in mind I've built a workaround for the autosweeper targeting falling ice. There are now two locations where ice can be targeted. (Third being the oddball ice at the vent when some cold automation was built there.)

 

This adjustment to the build has the autosweeper working correctly without targeting falling ice and picking up micro amounts of mass and bugging out.

I hope this information will come useful for those who love oddball builds.

Thank you for your time.

I am still going to try and track down what specifically changed to increase the frequency of hitting that infinite loop on your save eventually, it could be something errant in the event system refactor based on an inconclusive bisect, but the pathfinding issues that were coming up ended up taking priority to track down. The infinite loop the sweeper gets stuck in has always existed in the game and is the same one that people have noticed when filling solid oxidizer tanks with an autosweeper where a bit of the oxylite sublimates, resulting in a new fetch errand for the amount that sublimated, which also sublimates... but here it was the falling ice merged with the larger chunk resulting in a failed fetch, the new fetch gets issued right as a new chunk starts falling with the same mass so it gets targeted but merges before the auto sweeper can grab it and the cycle repeats. The reproducibility of the bug with your save at least on my work computer did fluctuate a bit with various unrelated performance improvements and regressions that have happened internally over the last month leading to the possibility that there isn't a relevant change behind the new behavior just a new timing window due to the optimization work however don't take that as gospel as other possibilities haven't been ruled out.

The question of the infinite loop being a bug or a reasonable behavior that needs to be engineered around is a bit of an open question too, either way changing that behavior won't be a candidate for a hotfix as it involves either changing the logic of pickupables merging or the internals of the fetch order structure, either of which will have widespread possible knock-on effects so it would have to be part of a major patch if it happens.

@HarryMcCleave:

Thank you very much for providing further insight into this particular tidbit of the game. I sort of suspected some issue with the autosweeper getting new targets and that causing the cascade of events as described in this thread.

This issue provided an excellent opportunity to refactor the build somewhat by putting different ideas into action and has thus made it even more efficient (subjectively speaking that is).

I've had an excellent couple of days addressing things going on somewhat sideways for this save file and am very happy with the results achieved as well as the care you're all extending this game that's already nearing a fine vintage state.