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Hang at specific FEN position #2091

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b9f9fe66 opened this issue Apr 12, 2019 · 2 comments

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commented Apr 12, 2019

q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
backtrace.txt
Seems to be an infinite loop at:

value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);

@b9f9fe66 b9f9fe66 changed the title Stockfish hangs at specific position Hang at specific FEN position Apr 12, 2019

@ddugovic

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commented Apr 12, 2019

Hang also reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

mcostalba added a commit that referenced this issue Apr 12, 2019

Revert "Shuffle detection #2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue #2091

Bench: 3243738
@mcostalba

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commented Apr 12, 2019

@b9f9fe66 @ddugovic thanks for reporting. Regression is confirmed and fixed here 5928cb2

@mcostalba mcostalba closed this Apr 12, 2019

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Apr 24, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Apr 27, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Apr 27, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Apr 29, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue May 2, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

MichaelB7 added a commit to MichaelB7/Stockfish that referenced this issue May 7, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue May 19, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue May 19, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue May 21, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue May 23, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Jun 19, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Jun 27, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738

mstembera pushed a commit to mstembera/Stockfish that referenced this issue Jun 27, 2019

Revert "Shuffle detection official-stockfish#2064"
It causes a serious regression hanging a simple fixed
depth search. Reproducible with:

position fen q1B5/1P1q4/8/8/8/6R1/8/1K1k4 w - - 0 1
go depth 13

The reason is a search tree explosion due to:

if (... && depth < 3 * ONE_PLY)
      extension = ONE_PLY;

This is very dangerous code by itself because triggers **at the leafs**
and in the above position keeps extending endlessly. In normal games
time deadline makes the search to stop sooner or later, but in fixed
seacrch we just hang possibly for a very long time. This is not acceptable
because 'go depth 13' shall not be a surprise for any position.

This patch reverts commit 76f1807.
and fixes the issue official-stockfish#2091

Bench: 3243738
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