[gnugo-devel] Re: GNUGo/kgsGtp Bug report

[William M. Shubert]

I think in this case, kgsGtp is doing the right thing, but I could be
misunderstanding how "undo" works.

My understanding is that each undo undoes exactly one move. So, if black
plays, then white, then the engine gets "undo", it should undo *only
white's last move*.

It looks like in this case kgsGtp sent an undo, and gnugo's next move
was on top of the last stone *before* the un-done move.

It is possible, though, that kgsGtp sent two undo's for some reason.
Nick, please run in verbose mode (which prints all communication between
kgsGtp and the engine), then if this happens again we'll know for sure
where the bug is.

On Sat, 2005-03-19 at 19:10 +0000, Nick Wedd wrote:
> GNU go people, Bill Shubert,
> 
> I am reporting a bug in either GNU Go release 3.9, or in kgsGtp, I
> cannot tell which.
> 
> On March 16th, GNU Go 3.6 (built by me from unmodified code downloaded
> from the GNU Go web site) was playing, as 'gnugo3pt6', from my PC, via
> kgsGtp, on KGS, against user 'skylancer'.  I have now examined the game
> record, which is attached.  The sequence of events appears to be
>   GNU Go plays at B9
>   skylancer plays at Q6
>   skylancer requests an undo, which is granted
>   skylancer plays at J13
>   GNU Go tries to play at B9 again, and gets booted
> This is odd.  KGS users often request undoes against gnugo3pt6, and it
> has not caused a problem before.
> 
> The last few lines of the kgsGtp output read
>    Time left: 16849
>    Out of time...waiting 10000
>    Out of time...waiting 10000
>    Time left: 16849
> 16-Mar-2005 16:39:31 org.igoweb.igoweb.client.gtp.GtpClient d
> FINE: Aborting command: genmove
>    Out of time...waiting 10000
> 16-Mar-2005 16:39:40 org.igoweb.igoweb.client.gtp.GtpClient d
> FINE: Ignoring response to aborted command: genmove
>    Time left: 16849
>    Out of time...waiting 10000
> 16-Mar-2005 16:39:56 org.igoweb.igoweb.client.gtp.GtpClient d
> SEVERE: Error from GTP Communications layer, closing down.
> org.igoweb.igoweb.client.gtp.F: Move "B9" from engine is not a legal
> move.
>          at org.igoweb.igoweb.client.gtp.ao.a(kgsgtp:751)
>          at org.igoweb.igoweb.client.gtp.ao.b(kgsgtp:39)
>          at org.igoweb.igoweb.client.gtp.aC.a(kgsgtp:717)
>          at org.igoweb.igoweb.client.gtp.an.b(kgsgtp:420)
>          at org.igoweb.igoweb.client.gtp.an.c(kgsgtp:288)
>          at org.igoweb.igoweb.client.gtp.an.a(kgsgtp:57)
>          at org.igoweb.igoweb.client.gtp.v.run(kgsgtp:184)
>          at java.lang.Thread.run(Unknown Source)
> 16-Mar-2005 16:39:57 org.igoweb.igoweb.client.gtp.GtpClient a
> FINE: Normal disconnection from server.