Hello, Consider this code:
open Printf let measure f = let t = Unix.gettimeofday () in let () = f () in printf "%.4f sec" (Unix.gettimeofday () -. t) let () = let gc () = for i = 1 to 10 do Gc.full_major () done in let a = Array.make 4_000_000 0 in measure gc; printf " normal %u (%u)\n%!" (Array.length a) (Gc.stat ()).Gc.live_words; Obj.set_tag (Obj.repr a) (Obj.no_scan_tag); measure gc; printf " no_scan_tag %u (%u)\n%!" (Array.length a) (Gc.stat ()).Gc.live_words; measure gc; printf " no array (%u)\n%!" (Gc.stat ()).Gc.live_words; () Output looks like : 0.2281 sec normal 4000000 (4000165) 0.0002 sec no_scan_tag 4000000 (4000165) 0.0002 sec no array (164) So, as expected, setting No_scan_tag on the array of integers prevents GC from uselessly scanning the huge chunk of memory. Looks like polymorphic array functions still work fine and GC correctly reclaims array memory when it is not referenced anymore. Apparantly this trick is not allowed for float array as they have a special tag set. The question is - how safe is this? And even more, could the compiler itself set this tag? -- ygrek http://ygrek.org.ua _______________________________________________ Caml-list mailing list. Subscription management: http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list Archives: http://caml.inria.fr Beginner's list: http://groups.yahoo.com/group/ocaml_beginners Bug reports: http://caml.inria.fr/bin/caml-bugs
