Dwarf Fortress Bug Tracker - Dwarf Fortress
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0008442Dwarf FortressPathfindingpublic2014-10-18 05:452017-05-06 14:37
choopm 
 
normalblockN/A
newopen 
x86_64Arch Linux-
0.40.13 
 
0008442: <5 FPS, 100% CPU Usage: Stuck dwarf interrupts others
I don't know exactly how to reproduce it, but it's the second time in 2 different regions, where a dwarf gets stuck in my stair tower:

It seems to be a pathfinding algorithm which eats up the CPU and let's the FPS drop towards 0 and so, leaves the game nearly unplayable.
I didn't notice if the dwarf got stuck before or after he was taken by a fey mood.
See the savegame: http://www.0pointer.org/~choopm/stuckmidair-region.zip [^]

It's my chief medical dwarf flying on -13 Z-levels from the wagon spawn (F1).
If k-looked onto the tile, it clearly says "Open Space".
I wonder how a stuck dwarf could interrupt other dwarves. If I zoom to the location hilighted in announcements, it takes me near where the dwarf should have been if he wasn't stuck.

Sorry for the few informations I could provide :(
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related to 0007998confirmed Footkerchief Area above mushroom "walls" classified as open space, dropping onto it causes you to fall forever then crash 
related to 0008324new  Imprisoned Were-creature brings FPS to crawling hold 
Issue History
2014-10-18 05:45choopmNew Issue
2014-10-18 05:47choopmIssue Monitored: choopm
2014-10-18 05:47choopmIssue End Monitor: choopm
2014-10-19 03:29choopmNote Added: 0030670
2014-10-19 06:35KirkegaardNote Added: 0030672
2014-10-19 09:55LacNote Added: 0030673
2014-11-19 12:36FootkerchiefRelationship addedrelated to 0007998
2017-05-06 14:37lethosorRelationship addedrelated to 0008324

Notes
(0030670)
choopm   
2014-10-19 03:29   
Update: I let the game up and running for a few hours.
The moment the chief medical dwarf went insane because of his dehydration it cancels the strange mood order. The game is now running smooth again.

So it seems the issue here might be:
If a dwarf get's into a strange mood and is trapped or stuck in your fortress, the pathfinding algorithm will be started over and over again. This results in 100% CPU usage and minimum FPS.

One approach could be a priority system, e.g. if a dwarf's path finding fails, it would get more and more less attention every frame iteration to a minimum where it would try to find a path every minute.
(0030672)
Kirkegaard   
2014-10-19 06:35   
I have also seen this, once with an cave swallow that somehow teleported itself into my stair area and tried to patch out. It can also happen if you use dfhack reveal and unreveal and some dwarfs get stuck in the "unknown area" instantly dropping fps to 0.
(0030673)
Lac   
2014-10-19 09:55   
We've had cases of stuck dwarfs in fey moods causing fps drop before; but they've been marked resolved: 0007284. Maybe Toady just addressed the sticking issue and there's other ways to get stuck.