KSudoku freezes when starting 25x25 game

Bug #552315 reported by Jeremiah on 2010-03-31
This bug affects 3 people
Affects Status Importance Assigned to Milestone
KDE Games
kdegames (Ubuntu)

Bug Description

Binary package hint: kdegames

I can start a game, but it freezes even before the puzzle is loaded.

Dude (computergeek2015) wrote :

I have the same problem. It also affects 16x16 for me.

Version: 0.5 (using KDE 4.4.4)
OS: Linux

When trying to start the games

Sudoku 16x16
Sudoku 25x25
Roxdoku 16 (4x4x4)
Roxdoku 25 (5x5x5)

the "Play"-button hangs (keeps pressed) and the game doesn't start.

Reproducible: Always

After waiting for ~20 seconds, Sudoku 16x16 finally starts.
Sudoku 25x25 didn't start within 8 minutes, so I stopped time measuring.
Seems like the game engine is doing some heavy work...

Dan McGrath (troubled) wrote :

I have this problem as well.

I did notice though that it happens somewhat randomly, and more often as you increase the number of tiles and/or the game difficulty. If I were to hazard a guess, I would think the game gets stuck in a loop trying to find a solvable map, since it takes up 100% of one core indefinitely.

Changed in kdegames (Ubuntu):
status: New → Confirmed

Danny McGrath's guess was correct. The execution loops in Puzzle::createPartial() until a solution is found.

I have made a upstream bug report: https://bugs.kde.org/show_bug.cgi?id=245756

Changed in kdegames:
status: Unknown → New

*** Bug 245756 has been marked as a duplicate of this bug. ***

Changed in kdegames:
status: New → Unknown
Changed in kdegames:
status: Unknown → Confirmed
Changed in kdegames:
importance: Unknown → High

*** Bug 278870 has been marked as a duplicate of this bug. ***

With KDE 4.9.4, this happens only noticable at difficulty level "unlimited".
I don't know if such a level really makes sense. If yes, there should be a status dialog with a "Cancel" button while creating the puzzle.

The new puzzle generator introduced in KDE SC 4.8 does not have this problem, except as you have observed in Unlimited difficulty mode. It encounters "road blocks" unpredictably during the generation process, instead of churning out and checking candidate puzzles regularly.

There is already a limit of 20 attempts to generate a puzzle with the type, size, difficulty and symmetry as ordered, after which KSudoku picks the best attempt so far and the user has the option to go on trying. Unlimited mode is just not getting that far on large-size puzzles. This is not right, but I cannot decide if it is worth investigating.

The point of Unlimited mode is for possible savants out there who have no problem with how many guessing and backtracking points there may be nor how soon the guessing has to start. The levels up to and including Hard normally require no guessing. These and the Diabolical level, which usually does require guessing, have been tested and calibrated against published puzzles in newspapers etc. My wife, who regularly does Hard and Diabolical puzzles, found Unlimited puzzles "inhuman" (i.e. tedious, very difficult and no fun) and my own experience was the same. That is why I introduced limits on guessing in the other levels.

Changed in kdegames:
status: Confirmed → Unknown

*** Bug 325199 has been marked as a duplicate of this bug. ***

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