OpenChess

Hello. Nice Forum, this is my first post here. Thanks to all the great people who contributed so much to computer chess, especially Dr Hyatt. While I claim no special talents besides being a chess enthusiast and humble EE, I would like to start out by offering an observation, and noting that if not careful, the tournament results in Arena 3.0 might be skewed due to hash size not remaining at the default.

I have noticed an issue with Arena 3.0 since I started using it last year, and on several different machines, and with all engines I have used, (except the Winboard based Crafty, obviously). The UCI default hash size does not always get retained during a tournament. The only way to insure the hash size stays at the correct value is to disable common hash table size, then configure the engines independently. Hash size can randomly revert to the size in the engine configuration, then randomly go back to the UCI default (well, I'm sure there is a reason, but to me it is random!). To be sure of accurate tournaments, do not use a common hash size, but instead, turn off UCI common hashtable size, then set all engines the same individually in their configuration. I am pretty sure this must not only be happening to me on multiple computers. Then again, maybe I made the same mistake configuring Arena (?) Murphy stalks me sometimes! Feedback is welcome.

Here is a picture showing it happening. Note that the time control is low for this game, as I did not want to wait during a test to capture it occuring, but it happens at all the time controls I have used.

If there is not enough memory available, many engines will fall back to a smaller size.
When I ask for a certain memory size and get something smaller, I generally find that a database engine on my machine has suddenly requested 5GB of RAM or some similar such thing.
If you see a memory request not being honored, check available RAM with Windows Task Manager.
I have about 9000 chess engines (I can't have all of them operational at once because no GUI that I know of allows that many). I am not about to manage each ini file individually, since they operate differently and I am far too lazy to try to learn a new procedure for each and every permutation (even within the same engine, options in initialization files vary from iteration to iteration).
I do, of course, use CTRL-1, after loading the engines, to set up the startup files for every engine, as far as my best guesses can take me.

-- User923005 From Planet Tralfamadore.

Hello User923005 from Tralfamadore!

I have plenty of physical memory left. I should have captured a screen with that showing, D'oh! The below image shows 3GB open on a 6GB machine. I should try the lottery today, as when I ran Arena 3.0 to get another capture of this happening, it was in the 2nd game (of an interpreted tournament), after a fresh boot . I did not have to wait long. I then stopped the tournament, and opened some windows to get a new improved picture.

User923005 wrote:I do, of course, use CTRL-1, after loading the engines, to set up the startup files for every engine, as far as my best guesses can take me.

Do you also use the common hash size? From your post it sounds like it, but I was not really sure. Do you set the hash for each engine every time you use Alt 1, etc?

Anyway, since I can't rely on the common setting, what I have been doing is making multiple engine copies with different hash sizes as needed, then renaming. I was hoping there was some trick to not have such a workaround, but I have not found it yet. BTW, I do not yet have 9000 engines (WOW, Holy $%#@), but find the need to have so many permutations a bit sloppy for my tastes.

It's a bug with Arena 3 tournaments.

To fix it, I setup "Restart Arena after so many games = 1" in tournament options...

Thanks, Odeus. I had the restart set at the recommended 20. I had once tried 10 and it still happened, so I will use your suggestion.

PS: I have a post pending approval with another screen shot, but now it's a moot point.