Write changelog for v0.19.0-rc1 (#484)

changelog.txt

@@ -1,3 +1,113 @@
+v0.19.0-rc1 (2018-11-03)
+~~~~~~~~~~~
+
+* Search algorithm changes
+
+  When visiting terminal nodes and collisions, instead of counting that as one
+  visit, estimate how many subsequent visits will also go to the same node, and
+  do a batch update.
+
+  That should slightly improve nps near terminal nodes and in multithread
+  configurations. Command line parameters that control that:
+
+  --max-collision-events – number of collision events allowed per batch.
+    Default is 32. This parameter is roughly equivalent to
+    --allowed-node-collisions in v0.18.
+
+  --max-collision-visits – total number of estimated collisions per NN batch.
+    Default is 9999.
+
+* Time management
+
+  Multiple changes have been done to make Leela track used time more precisely
+  (particularly, the moment when to start timer is now much closer to the moment
+  GUIs start timer).
+
+  For smart pruning, Leela's timer only starts when the first batch comes from
+  NN eval. That should help against instamoves, especially on non-even GPUs.
+
+  Also Leela stops the search quicker now when it sees that time is up (it could
+  continue the search for hundreds of milliseconds after that, which caused time
+  trouble if opponent moves very fast).
+
+  Those changes should help a lot in ultra-bullet configurations.
+
+* Better logging
+
+  Much more information is outputted now to the log file. That will allow us to
+  easier diagnose problems if they occur. To have debug file written, add a
+  command line option:
+
+  --logfile=/path/to/logfile
+
+  (or short option "-l /path/to/logfile", or corresponding UCI option "LogFile")
+
+  It's recommended to always have logging on, to make it easier to report bugs
+  when it happens.
+
+* Configuration parameters change
+
+  Large part of parameter handling has been reworked. As the result:
+
+  All UCI parameters have been changed to have more "classical" look.
+    E.g. was "Network weights file path", became "WeightsFile".
+
+  Much more detailed help is shown than before when you run
+    ./lc0 --help
+
+  Some flags have been renamed, e.g.
+    --futile-move-aversion
+    is renamed back to
+    --smart-pruning-factor.
+
+  After setting a parameter (using command line parameter or uci setoption
+    command), uci command "uci" shows updated result. That way you can check the
+    current option values.
+
+  Some command-line and UCI options are hidden now. Use --show-hidden command
+    line parameter to unhide them. E.g.
+    ./lc0 --show-hidden --help
+
+  Also, in selfplay mode the per player configuration format has been changed
+  (although probably noone knew that anyway):
+    Was: ./lc0 selfplay player1: --movetime=14
+    Became: ./lc0 selfplay --player1.movetime=14
+
+* Other
+
+  "go depth X" uci command now causes search to stop when depth information in
+  uci info line reaches X. Not that it makes much sense for it to work this way,
+  but at least it's better than noting.
+
+  Network file size can now be larger than 64MB.
+
+  There is now an experimental flag --ramlimit-mb. The engine tries to estimate
+  how much memory it uses and stops search when tree size (plus cache size)
+  reaches RAM limit. The estimation is very rough. We'll see how it performs and
+  improve estimation later.  
+  In situations when search cannot be stopped (`go infinite` or ponder),
+  `bestmove` is not automatically outputted. Instead, search stops progress and
+  outputs warning.
+
+  Benchmark mode has been implemented. Run run, use the following command line:
+    ./lc0 benchmark
+  This feature is pretty basic in the current version, but will be expanded later.
+
+  As Leela plays much weaker in positions without history, it now is able to
+  synthesize it and do not blunder in custom FEN positions. There is a
+  --history-fill flag for it. Setting it to "no" disables the feature, setting
+  to "fen_only" (default) enables it for all positions except chess start
+  position, and setting it to "always" enables it even for startpos.
+
+  Instead of output current win estimation as centipawn score approximation,
+  Leela can how show it's raw score. A flag that controls that is --score-type.
+  Possible values:
+    - centipawn (default) – approximate the win rate in centipawns, like Leela
+      always did.
+    - win_percentage – value from 0 to 100.0 which represents expected score in
+      percents.
+    - Q – the same, but scales from -100.0 to 100.0 rather than from 0 to 100.0
+
 v0.18.1 (2018-10-02)
 ~~~~~~~