TCEC Division 2/Arasan

[jdart]

TCEC Division 2 is still ongoing. Arasan is participating but was disqualified after disconnecting three times (other engines have also had disconnects but so far no one else has three). I have been following the chat but I am not participating because it apparently requires login with Facebook, and I don't do Facebook.

FYI: Arasan in this edition is a dev version running with new multithreading code based on LazySMP. I have spent a good part of last month working on this and it is stable enough that it has been playing on the chess servers (ICC and FICS) with no issues, on 4-8 cores. But it has not really been tested well on the very high core counts that TCEC uses. So I think the new code is likely the cause of pretty much all the issues. The good news is that in the games it was able to complete using all 44 cores, it was performing quite well (over 50M NPS). But the TCEC version evidently isn't stable. I have committed a few changes since the release to TCEC but am still testing/fixing things.

--Jon

[AndrewGrant]

Asking for myself and for Can (DefenChess),

Do you think any of the stability issues relate to TB, or just the reworked SMP?

I wish you the best of luck. Arasan might have the oldest roots of any engines in TCEC

-- Andrew

[jdart]

I don't know of any issue in the Fathom code that is used for TB access.

I did put a fix into that fairly recently for a problem that showed up in testing the LazySMP code (basically, locking was not working). But that was really a fix, and shouldn't have caused any new issues.

I am suspecting that since the LazySMP code really increases concurrent access to the hashtable, that I am seeing some crashes due to that. For example, right now it validates the hash move but it tries to do that later in the search code, after it has been fetched, and if it is really badly corrupted that may not be sufficient. I am testing a change that does a full validation right away. If so this is a problem specific to Arasan.

--Jon

[elcabesa]

Hi Jon,
If you want I can run some games with a rasa on my dual E5 - 2620 six core.I was able to run Vajolet at 23 thread without any problem. It's a Linux machine. Let me know of you need help

[zenpawn]

TCEC Division 2 is still ongoing. Arasan is participating but was disqualified after disconnecting three times (other engines have also had disconnects but so far no one else has three). I have been following the chat but I am not participating because it apparently requires login with Facebook, and I don't do Facebook.

The chat is from Twitch, so creating an account at twitch.tv also works.

[jdart]

Hi Jon,
If you want I can run some games with a rasa on my dual E5 - 2620 six core.I was able to run Vajolet at 23 thread without any problem. It's a Linux machine. Let me know of you need help

Thanks for the offer but I actually have several big machines, including a 32-core AMD system.

--Jon