Nim is moving to more efficient memory management models: ARC and ORC. Let's find out exactly how they will change the way it works with memory.
Introduction
Hello! In this article I will try to explain what ARC and ORC are and how they affect performance or other parts of Nim. I will not go deeply into the aspects of the software part, but will try to give a more or less high-level explanation.
Let's start from afar: Nim has always been a garbage collector (GC) language. Of course, GC can be turned off, but then when working with most of the standard library ( and it is rather big ) memory will leak.
GC Nim refc ( mark & sweep ), , markAndSweep, boehm, go, regions.
Nim' , , (owned ref) :
, Nim ARC
ARC?
ARC , (Automatic Reference Counting) (move semantics). , ARC Nim , ARC Swift, — Nim ARC .
. ( runtime) , . , .
ARC GC Nim , ARC — (, , , .), . ARC C++ (RAII)
, , ARC expandArc, Nim 1.4.
Nim:
proc main =
let mystr = stdin.readLine()
case mystr
of "":
echo "!"
of "":
echo "!"
quit()
else:
discard
main() nim c --gc:arc --expandArc:main example.nim.
--expandArc: main
var mystr
try:
mystr = readLine(stdin)
case mystr
of "":
echo ["!"]
of "":
echo ["!"]
quit(0)
else:
discard
finally:
`=destroy`(mystr)
-- end of expandArc ------------------------ — Nim main try: finally ( finally , try ) =destroy mystr, .
ARC: (scope-based MM). — . , , , . Nim' : , , , , block, for while .
ARC hooks — , , // . , , , FFI.
refc ARC ( ):
( ) — .
— , .
—
refc, (thread-local heap), ARC . — . RFC , ARC.
FFI — ,
refc"" (.. ) , ARC. , ARC , (.dll, .so, Python' )
-
(copy elision), Nim (cursor inference) — ()
, ARC Nim , , , .
, ARC , , , --gc:arc, (.nims .cfg).
! - ? ARC , , , . — , , . : 3 (A, B, C), , :
, , — , , .
Nim' mark & sweep refc GC, ARC - . :
ORC — Nim
ORC , ARC. GC, (local tracing phase) GC, (global tracing).
async Nim ORC, Nim' , .
ORC ARC () — ORC , hard realtime ( ) — .
ORC --gc:orc, , ORC GC Nim'
! ?
— — Nim 1.4. .
! — , !
/ :