From: Marco Costalba <mcostalba@gmail.com>
Date: Sun, 24 Jan 2010 12:46:27 +0000 (+0100)
Subject: Fix some races in SMP code
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=3975a2b94f00dc9f3ead1589436256a39120368a;hp=3975a2b94f00dc9f3ead1589436256a39120368a

Fix some races in SMP code

When a search fails high then sp->alpha is increased and
slave threads are requested to stop.

So we have to check for a stop request before to start a search
otherwise we could end up with sp->alpha >= sp->beta
leading to an assert in debug run in search_pv().

This patch fixes the assert and get rid of some of possible races.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
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