🚀 go-pugleaf

$@EDCf$5$s!w(JRWCP writes:

 > >>
 > >>   $@$3$l$b;d$K$H$C$F$O<+L@$G$O$J$$$G$9(J. mark & sweep$@$G$b(Jcopy$@J}<0$G$b(J
 > >>   incremental$@$K$9$k;~$N(Jcost$@$O2?$i$+$N(J read barrier $@$J$$$7(Jwrite barrier 
 > >>   $@$G(J, $@$=$l$O(J mark & sweep $@$+(J copy $@J}<0$+$G$+$o$k$b$N$G$O$J$$$H;W$$$^$9(J.
 > >>
 > >>   $@$I$NEv$?$j$rHf(J$@3S$7$F$$$i$C$7$c$k$N$G$7$g$&$+(J?
 > 
 > 	   $@$*$C$7$c$kDL$j!$(Jmark & sweep$@J}<0$r%Y!<%9$K$9$l$P(Jwrite barrier
 > 	   $@$K$J$j!$(Jcopy$@J}<0$r%Y!<%9$K$9$l$P(Jread barrier$@$K$J$j$^$9!%(J
 > 
 > 	   copy$@J}<0%Y!<%9$NJBNs(JGC$@$r<BAu$7$?$3$H$O$J$$$N$G<B83E*$KHf3S$r9T(J
 > 	   $@$J$C$?$3$H$O$"$j$^$;$s$,!$$I$A$i$NJ}$,8zN($,NI$$$+$O(Jread
 > 	   barrier$@$H(Jwrite barrier$@$N$I$A$i$,B?$/H/@8$9$k$+$K$h$C$F7h$^$k$N(J
 > 	   $@$G$O$J$$$G$7$g$&$+!%(J$@$=$7$F!$$d$O$j(Jread barrier$@$NJ}$,=E$$$+$J$H(J
 > 	   $@;W$$$^$9!%(J

$@$o$+$j$^$7$?(J. $@3N$+$K<BAu$NJ#;($5$^$G9M$((J$@$k$H(J, mark & sweep$@$NJ}$,(J, $@AGD>(J
$@$K(Jwrite barrier$@$G<B8=$G$-(J, real time$@$K$O8~$$$F$$$k$H$$$&E@$O(J, $@$"$k$G$7(J$@$g(J
$@$&(J. $@$"$^$j$h$/9M$($:$KH/8@$7$F$7$^$$$^$7$?(J.

$@$?$@$7G0$N$?$a(J, copy$@J}<0$G$b(Jwrite barrier$@$K$9$k$3$H$O(J$@2DG=$G$9(J. 

$@>/$7@0M}$5$;$F2<$5$$(J.

copy$@J}<0$@$HF10l$N(Jobject$@$KBP$7$F(J, 
(1) to space$@$K(Jcopy$@$5$l$?(Jobject$@$H(Jfrom space$@$K;D$C$F$$$k(Jversion$@$H$G(J
consistency$@$r$H$i$J$/$F$O$$$1$J$$(J,
(2) from space$@$N(Jheader$@ItJ,$ODL>o(Jforwarding pointer$@$GDY$5$l$k(J

$@$N$G8EE5E*$K$O(J, mutator$@$,(Jto space$@$@$1$r8+$k$h$&$K$9$k(J($@$D$^$j(J, read
barrier)$@J}<0$,9T$J$o$l$k$o$1$G$9$,(J, $@$3$l$i$NLdBj$r(Jclear$@$G$-$l$P(Jwrite
barrier$@$K$b$G$-$k$o$1$G$9(J.

(1) $@$O(J, mutator$@$,>o$K(J, $@!V(Jfrom space$@!W$r8+$k$h$&$K$7$F(J, $@$+$D(Jmutation$@$r(J
collector$@$,8e$+$i(Jto space$@$KH?1G$5$;$k$3(J$@$H$GBP=h$7$F(J($@$3$l$O$I$N$_$AI,MW(J),
(2)$@$K$D$$$F$O(J, (a) $@3F(Jobject$@$K(Jforwarding pointer$@$N$?$a$N6u$-(Jword$@$r$D(J$@$1(J
$@$k(J, $@$^$?$O(J, (b) $@DY$5$l$F$$$k$+$bCN$l$J$$(Jword$@$rFI$`;~$O(Jforwarding$@$5$l$?(J
$@@h$rFI$`$h$&$K$9$k(J

$@$3$H$GBP(J$@=h$G$-$^$9(J. Toole$@$N(JConcurrent Replicating GC [1]$@$,$3$l$r(J
$@$d$C$F$$$^$9(J. 

## $@$b$A$m$s(J, $@$3$NJ}<0$,$$$$$N(J$@$@$H@Q6KE*$K<gD%$O$G$-$^$;$s(J. $@L@$i$+$K(J
mutation$@$,Hs>o$K5)$G$O$"$k$H$$$&$3$H$K0MB8$7$F$$$^$9(J(Toole$@$N<B(J$@Au$O(J
SML/NJ$@MQ$N$b$N$G$9(J). $@C1$K(Jread barrier$@$,=E$$$+$i(J mark & sweep $@$H$$$&$3(J
$@$H$K$O$J$i$J$$(J, $@$H$$$&$@$1(J$@$N$3$H$G$9$M(J.

$@$=$l$>$l$NJ}<0$NLdBjE@$r$^$H$a$k$H(J, 

Mark Sweep + write barrier: 	allocation$@$,CY$$(J
Copy + write barrier:		space overhead$@$^$?$O(Jindirection
				overhead, consistency$@0];}$N(Joverhead
Copy + read barrier:		read$@$O(Jwrite$@$h$j$bIQHK$G(J, software
				check$@$O=E$$(J. Protection$@$O(Jpagewise$@$K$7(J
				$@$+$G$-$J(J$@$$(J. $@$$$:$l$K$;$h(Jreal time$@$rJ](J
				$@>Z$G$-$k$+5?Ld(J 

$@$H$$$&$3$H$K$J$k$G$7$g$&$+(J. Lisp program$@$O(Jallocation intensive$@$G$9$7(J
mutation$@$b%P%s%P%s$*$-$k$N$G(J, GC$@$K$H$C$F$O0lHV(Jchanllenging$@$G$9$M(J.

[1]:
@InProceedings{Toole94Cuncurrent,
  author = 	 "James O'Toole and Scott Nettles",
  title = 	 "Concurrent Replicating Garbage Collection",
  pages = 	 "34--42",
  booktitle = "Conference Record of the 1994 {ACM} Symposium on
		  Lisp and Functional Programming",
  year = 	 1994
}
--
		Kenjiro Taura
		Yonezawa Laboratory, Department of Information Science 
		Tokyo University
		tau@is.s.u-tokyo.ac.jp