Author: Robert Hyatt
Date: 15:25:39 07/22/03
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On July 22, 2003 at 17:43:03, Matthew Hull wrote: >On July 22, 2003 at 17:27:37, Bob Durrett wrote: > >> >>While using Chessbase 8, I use an analysis engine. Until today, that analysis >>engine has been Fritz 8. Today I purchased Shredder 7 and ran Chessbase 8 using >>Shredder 7 as the analysis engine. After allowing the analysis engine to look >>at a position for a few minutes, I copied the Shredder line to the notation and >>then switched to Fritz 8. The question I have is whether or not the contents of >>the hash table used by Shredder would then be used by Fritz. The first thought >>would be that switching engines would erase the Shredder hash table(s) and set >>up new empty Fritz hash table(s). But does it have to be that way? > > >The hash table is part of the program's memory address space. Each program has >it's own address space. There is no sharing of this space between chess >engines. Most modern operating systems take care that one address space does >not access another program's address space, as this would defeat the goals of >system stability and program reliability in spectacular ways. > >Regards, >Matt > > Yes, but a program +could+ do this without knowing. IE let the GUI create (allocate) the hash table. It could use shmget/shmat to create a _shared_ block of memory that another engine could use once the first engine is terminated. Or it could use mmap() to do the same thing. It is highly doubtful it is done, of course, but it _is_ possible. >> >>Is there some simple test a user could perform to determine whether or not the >>two engines would use the same hash table where the contents put in by one >>engine would then be used by the other? >> >>Does this make any sense? >> >>Bob D.
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