Multithreaded search - possibilities

[portnov]

• Naive approach: at first step, create a separate thread for each possible move.
  • pro: easy to implement
  • pro: not so bad for rules that do not have very big branching degree (russian, english)
  • con: each thread has to be run with full [alpha; beta] window
• Modified naive approach: create a separate thread for each bunch of N possible moves. For example, split all moves into 4 threads.
  • pro: easy to implement
  • pro: there is visible improvement comparing to naive approach for rules with very high branching degree (turkish, armenian)
  • con: does not show any visible advantage for rules with low branching degree, comparing to naive approach
  • con: still too wide window for many moves
• Modified approach 2: create one thread for all but (N-1) moves; for each of (N-1) moves left, create separate thread.
  • pro: shows visible improvement for russian rules
  • con: in some cases, this degrades into one-thread calculation

See: https://www.chessprogramming.org/Parallel_Search