Workers/dozers suddenly stop moving despite being ordered to move to a location

[nhatter]

Area(s) with this issue?

Zero Hour v1.04

Describe the issue

On Zero Hour, especially when I play Twilight Flame, I notice at times even when I've ordered a worker/dozer to move to a location, they sometimes suddenly stop - and then I have to order them to move again!

I don't know if this is just in the start of the game.

But it can be frustrating (although mismatch + random game crashes more so!)

Steps to reproduce

1. Order a bunch of GLA workers or USA/China dozers to move to a location on a map like Twilight Flame
2. Occasionally, one or more worker/dozer(s) will stop moving after being ordered (and you will have to manually order them to move again)

Attachments

No response

[real2nabeel]

I was able to reproduce as seen in the attachment.

dozer_stuck.mp4

[xezon]

This happens when there is a lot of stuff going on the map, right?

[real2nabeel]

@xezon not necessarily, check my attachment, I only had a few dozers and it happened

[Caball009]

This is still reproducible with the latest version of the main branch.

I found this the easiest way to reproduce:

1. Choose China faction; doesn't seem to matter which map.
2. Build a nuclear reactor and build the radar on the command center.
3. Once both are finished, build two construction dozers.
4. When the first one is finished building, let it move until it's almost off the building site and then order it to other side of the map so that it moves directly through the construction hall it came from. Once the second dozer is finished building move it immediately to the same location as the first.
5. Second dozer stops a short distance from the command center.

It's key that the dozers move through the command center as far as I can tell.

[Caball009]

@Mauller Would you mind checking if this related to pathfinding?

[Mauller]

The problem that causes this depends on where the units are being order to move and if there are a lot of buildings placed on the map already.

If it's the start of the game and a unit is being ordered to move across the gorge, the pathfinding does not have enought resources to map a path to the other side, so the unit will often move and get stuck on the near side of the gorge.

If it's late game then units stop due to pathfinding resources running out due to another issue where buildings and objects placed on the maps use pathfinding resources up reducing the limited pool of available resources.

[Caball009]

dozer_unexpected_stop.mp4

@Mauller This doesn't look like the ordinary pathfinding issues we're familiar with, though.

[Mauller]

Yes i don't think this is to do with pathfinding in the way i was thinking, i think this is a mix of AI states when the unit is exiting the construction building and avoidance code.

I think we will want to make a change in the future to make units inactive till they fully exit a production building.
Also a change to prevent another unit spawning on the production building till the previous unit has vacated first.