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Up Topic The Rybka Lounge / Computer Chess / BUG REPORT CRYSTAL-201108 Bench position #38 if multi-thread
- By MrKris (***) Date 2020-11-21 23:55
Stockfish and Cyrstal bench position #38 (checked to be the same) :
in Crystal-201108-avx2 hangs with multi-threading:
the higher the threads the lower the depth possible,
single thread okay at depth 25 and 28.
Hangs if 4-threads and

8/3k4/8/8/8/4B3/4KB2/2B5 w - - 0 1


Ryzen 7 2700X 8-cores/16-SMT (Ubuntu 20.04)
Linux terminal:

bench ============= Crystal-201108-avx2
Total time (ms) : 5035
Nodes searched  : 7300914
Nodes/second    : 1450032 {bench okay of course}
__________________________________________________________________________

bench 256 14 22 === Crystal-201108-avx2
   ... ... ...
Position: 37/47 '8/8/8/5N2/8/p7/8/2NK3k w - - 0 1' 
                                      (' instead of () suppresses the board generation this forum}
Position: 38/47 '8/3k4/8/8/8/4B3/4KB2/2B5 w - - 0 1'  {#38}

@@>> ERROR if 22 plies: indefinite hang with all 14 threads 100% <<@@
^C {NO OUTPUT until keyboard Control-C quits engine and prompt re-appears}
$
__________________________________________________________________________

bench 256 14 21 === Crystal-201108-avx2
Total time (ms) : 16571
Nodes searched  : 304656177
Nodes/second    : 18384899  {14-threads, 21 ply okay}
__________________________________________________________________________

Crystal-201108-avx2
@ 1-thread:
position fen '8/3k4/8/8/8/4B3/4KB2/2B5 w - - 0 1'  {#38, 's added}
go depth 25
... info depth 25 seldepth 50 multipv 1 score cp 1182 nodes 58153097 nps 1972561 hashfull 1000 tbhits 0 time 29481 pv e2d3 ...
bestmove e2d3 ponder d7c6 {25 plies okay}

go depth 28
... info depth 28...time 851052
bestmove e2d3 ponder d7c6  {28 plies okay -- but 29 times longer than ply 25 --}
__________________________________________________________________________

@ 4-threads (quit and restarted 1st) :
setoption name threads value 4
position fen '8/3k4/8/8/8/4B3/4KB2/2B5 w - - 0 1'  {#38, 's added}
go depth 25
... info depth 24 currmove e2d3 currmovenumber 1
info depth 24 seldepth 101 multipv 1 score cp 1336 lowerbound nodes 127626971 nps 6284566 hashfull 1000 tbhits 0 time 20308 pv e2d3
info depth 24 currmove e2d3 currmovenumber 1
^C {ERROR: no output for 300+ seconds, 4 threads @ 100%, until Control-C quits & returns to terminal}
$
__________________________________________________________________________

@ 14-threads :
setoption name threads value 14
position fen '8/3k4/8/8/8/4B3/4KB2/2B5 w - - 0 1'  {#38, 's added}
go depth 25
... info depth 20 seldepth 87 multipv 1 score cp 1168 lowerbound nodes 354504828 nps 10742896 hashfull 1000 tbhits 0 time 32999 pv e2d3
info depth 20 currmove e2d3 currmovenumber 1
^C {ERROR: no output for 300+ seconds, 14 threads @ 100% until Control-C quits & returns to terminal}
$
Up Topic The Rybka Lounge / Computer Chess / BUG REPORT CRYSTAL-201108 Bench position #38 if multi-thread

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