Author: Vincent Diepeveen
Date: 07:25:17 05/17/01
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On May 16, 2001 at 00:18:42, Bruce Moreland wrote: >On May 15, 2001 at 20:28:25, Sam Gross wrote: > >>I am writing a bitboard-based chess engine in Java, and a preliminary test of >>the search function (plain alpha-beta search, no transposition table, history, >>null move, or anything else) was pretty disappointing. I am getting about 10% >>of the nps crafty gets on the same machine, even though my evaluation function >>is just the material imbalance. My question is, how much of this is due to >>differences in speed between Java and C++, and how much is due to lack of a >>transposition table (or other factors)? Also, I wonder if my program may be >>stretching Java's automatic garbage collectors. A new copy of my board is made >>for every node, and each node creates many instances of my move object, which I >>imagine would use up a lot of time. Any help would be appreciated. > >"new" is evil if it's used in an important part of a performance intensive >application. > >It would be much more efficient to make an array of these things, and increment >and decrement a pointer into the array when you enter and leave a node. > >bruce I'm not a big JAVA expert but a major problem of JAVA is that it doesn't have pointers. The only way to index an array is by means of a[i] anything like next is not working: *(a+i) , *a++ = i , a = &movearray[i]; Nevertheless the few experiments i did with java over the course of one full year (whole project in JAVA) i did get nullpointer after nullpointer... ...which theoretical is not possible in JAVA as it has no pointers... You can ask a pointer from the system, but that's not how we WANT to use a pointer in a chessprogram. In short i quickly understood that JAVA will be never able to optimize a program to the same extend as a C++ compiler can. A big penalty there will always be for using JAVA. C++ rules. Best regards, Vincent
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