[Pachi] MAC regression bug: segmentation fault

jonathan chetwynd j.chetwynd at btconnect.com
Sat May 28 12:13:42 CEST 2011


attached gdb output for: 75dd178099bef5f3d426040d124bbd56a2b2aafd

~:"

$ gdb --args ./pachi threads=4
GNU gdb 6.3.50-20050815 (Apple version gdb-1515) (Sat Jan 15 08:33:48 UTC 2011)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin"...Reading symbols for shared libraries .. done

(gdb) run
Starting program: /Users/jaymini/pachi-seg/pachi threads=4
Reading symbols for shared libraries +. done
Random seed: 1306588521
genmove black
IN: genmove black
Fresh board with random seed 1306588521

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000147fffffc
[Switching to process 16253]
0x000000010002bb49 in ucb1amaf_update (p=<value temporarily unavailable, due to optimizations>, tree=0x100100490, node=0x101000000, node_color=S_WHITE, player_color=<value temporarily unavailable, due to optimizations>, map=0x148002c00, final_board=0x10077cd00, result=0) at ucb1amaf.c:197
197				stats_add_result(&node->winner_owner, board_at(final_board, node->coord) == winner_color ? 1.0 : 0.0, 1);
(gdb) bt
#0  0x000000010002bb49 in ucb1amaf_update (p=<value temporarily unavailable, due to optimizations>, tree=0x100100490, node=0x101000000, node_color=S_WHITE, player_color=<value temporarily unavailable, due to optimizations>, map=0x148002c00, final_board=0x10077cd00, result=0) at ucb1amaf.c:197
#1  0x0000000100029e6a in uct_playout (u=0x100100090, b=0x100800000, player_color=S_BLACK, t=0x100100490) at walk.c:431
(gdb) Quit
The program is running.  Exit anyway? (y or n) y
mac-mini:pachi-seg jaymini$ 

  	
Jonathan Chetwynd

j.chetwynd at btconnect.com
http://www.peepo.com/

+44 (0) 20 7978 1764


On 27 May 2011, at 21:13, Petr Baudis wrote:

> 
>  Hi!
> 
> On Fri, May 27, 2011 at 07:38:12PM +0100, jonathan chetwynd wrote:
>> not sure if there is a regular bug filing app in place....
> 
>  The mailing list. ;-)
> 
>> in the meantime
>> 
>> 2 bugs on new 15" mac pro 4 core one processor
>> latest OS X, Xcode and fully up to date.
>> both pachi built fine with no errors using MAC=1 only edit:
>> 
>> 4df88f81de79620926a27410e0948fa4092c5bca
>> 
>> ./pachi
>> runs fine, 
>> 
>> and
>> 
>> ./pachi threads=2
>> runs fine
>> 
>> but 
>> 
>> ./pachi threads=4 causes segmentation fault
>> on genmove black  
>> ie 9x9 standard
> 
> Hmm, curious. Would it be possible to run Pachi in a debugger, or
> analyze the core dump? At least to get a backtrace (i.e. where within
> the code Pachi crashed). I'm not familiar with Xcode, but if there is
> 'gdb' tool installed, just
> 
> 	gdb --args ./pachi threads=4
> 	> run
> 	... let it crash ...
> 	> bt
> 
>> regression
>> 
>> 75dd178099bef5f3d426040d124bbd56a2b2aafd
>> 
>> ./pachi causes segmentation fault
>> on genmove black  
>> ie 9x9 standard
> 
> Most curious! Is 'genmove black' the very first command, or do you issue
> some initialization commands as well?
> 
> The only relevant change is addition of 'fixed_handicap' to the list of
> known commands, but I have no idea how this could be related.
> 
> -- 
> 				Petr "Pasky" Baudis
> UNIX is user friendly, it's just picky about who its friends are.

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