From b36b4b521f53e5ff2e18fff3c194d28f9a840868 Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Tue, 22 May 2012 14:32:25 -0300
Subject: try to avoid sweeping new objects created with new white (and
therefore not collectable in the current cycle)
---
lgc.c | 62 ++++++++++++++++++++++++++++++++++++++------------------------
lstate.c | 3 ++-
lstate.h | 5 +++--
3 files changed, 43 insertions(+), 27 deletions(-)
diff --git a/lgc.c b/lgc.c
index 435c5e48..9831dce9 100644
--- a/lgc.c
+++ b/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 2.123 2012/05/20 20:36:44 roberto Exp roberto $
+** $Id: lgc.c,v 2.124 2012/05/21 13:18:10 roberto Exp roberto $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -49,6 +49,7 @@
#define workrate(x,mul) \
((x) < MAX_INT/80 ? ((x) * 80) / mul : ((x) / mul) * 80)
+
/*
** standard negative debt for GC; a reasonable "time" to wait before
** starting a new cycle
@@ -738,19 +739,16 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
freeobj(L, curr); /* erase 'curr' */
}
else {
+ if (testbits(marked, tostop))
+ return NULL; /* stop sweeping this list */
if (gch(curr)->tt == LUA_TTHREAD)
sweepthread(L, gco2th(curr)); /* sweep thread's upvalues */
- if (testbits(marked, tostop)) {
- static GCObject *nullp = NULL;
- p = &nullp; /* stop sweeping this list */
- break;
- }
/* update marks */
gch(curr)->marked = cast_byte((marked & toclear) | toset);
p = &gch(curr)->next; /* go to next element */
}
}
- return p;
+ return (*p == NULL) ? NULL : p;
}
/* }====================================================== */
@@ -865,7 +863,7 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
GCObject **p;
GCheader *ho = gch(o);
/* avoid removing current sweep object */
- if (g->gcstate == GCSsweep && g->sweepgc == &ho->next) {
+ if (g->sweepgc == &ho->next) {
/* step to next object in the list */
g->sweepgc = (ho->next == NULL) ? NULL : &gch(ho->next)->next;
}
@@ -892,6 +890,24 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
#define sweepphases \
(bitmask(GCSsweepstring) | bitmask(GCSsweepudata) | bitmask(GCSsweep))
+
+/*
+** enter first sweep phase (strings) and prepare pointers for other
+** sweep phases. The calls to 'sweeplist' attempt to make pointers
+** point to an object inside the list (instead of to the header), so
+** that the real sweep do not need to skip objects created between "now"
+** and the start of the real sweep.
+*/
+static void entersweep (lua_State *L) {
+ global_State *g = G(L);
+ g->gcstate = GCSsweepstring;
+ lua_assert(g->sweepgc == NULL && g->sweepfin == NULL);
+ g->sweepstrgc = 0; /* prepare to sweep strings, ... */
+ g->sweepfin = sweeplist(L, &g->finobj, 1); /* finalizable objects, ... */
+ g->sweepgc = sweeplist(L, &g->allgc, 1); /* and regular objects */
+}
+
+
/*
** change GC mode
*/
@@ -907,9 +923,8 @@ void luaC_changemode (lua_State *L, int mode) {
else { /* change to incremental mode */
/* sweep all objects to turn them back to white
(as white has not changed, nothing extra will be collected) */
- g->sweepstrgc = 0;
- g->gcstate = GCSsweepstring;
g->gckind = KGC_NORMAL;
+ entersweep(L);
luaC_runtilstate(L, ~sweepphases);
}
}
@@ -972,9 +987,8 @@ static void atomic (lua_State *L) {
/* clear values from resurrected weak tables */
clearvalues(g, g->weak, origweak);
clearvalues(g, g->allweak, origall);
- g->sweepstrgc = 0; /* prepare to sweep strings */
- g->gcstate = GCSsweepstring;
g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
+ entersweep(L); /* prepare to sweep strings */
/*lua_checkmemory(L);*/
}
@@ -1010,25 +1024,22 @@ static lu_mem singlestep (lua_State *L) {
for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
g->sweepstrgc += i;
- if (g->sweepstrgc >= g->strt.size) { /* no more strings to sweep? */
- g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */
+ if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */
g->gcstate = GCSsweepudata;
- }
return i * GCSWEEPCOST;
}
case GCSsweepudata: {
- if (*g->sweepgc) {
- g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
+ if (g->sweepfin) {
+ g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
return GCSWEEPMAX*GCSWEEPCOST;
}
else {
- g->sweepgc = &g->allgc; /* go to next phase */
g->gcstate = GCSsweep;
return 0;
}
}
case GCSsweep: {
- if (*g->sweepgc) {
+ if (g->sweepgc) {
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
return GCSWEEPMAX*GCSWEEPCOST;
}
@@ -1121,16 +1132,19 @@ void luaC_step (lua_State *L) {
void luaC_fullgc (lua_State *L, int isemergency) {
global_State *g = G(L);
int origkind = g->gckind;
+ int someblack = keepinvariant(g);
lua_assert(origkind != KGC_EMERGENCY);
- if (!isemergency) /* do not run finalizers during emergency GC */
+ if (isemergency) /* do not run finalizers during emergency GC */
+ g->gckind = KGC_EMERGENCY;
+ else {
+ g->gckind = KGC_NORMAL;
callallpendingfinalizers(L, 1);
- if (keepinvariant(g)) { /* marking phase? */
+ }
+ if (someblack) { /* may there be some black objects? */
/* must sweep all objects to turn them back to white
(as white has not changed, nothing will be collected) */
- g->sweepstrgc = 0;
- g->gcstate = GCSsweepstring;
+ entersweep(L);
}
- g->gckind = isemergency ? KGC_EMERGENCY : KGC_NORMAL;
/* finish any pending sweep phase to start a new cycle */
luaC_runtilstate(L, bitmask(GCSpause));
/* run entire collector */
diff --git a/lstate.c b/lstate.c
index 0a61ea1a..fecd0fba 100644
--- a/lstate.c
+++ b/lstate.c
@@ -1,5 +1,5 @@
/*
-** $Id: lstate.c,v 2.93 2012/02/01 21:57:15 roberto Exp roberto $
+** $Id: lstate.c,v 2.94 2012/05/11 14:06:07 roberto Exp roberto $
** Global State
** See Copyright Notice in lua.h
*/
@@ -292,6 +292,7 @@ LUA_API lua_State *lua_newstate (lua_Alloc f, void *ud) {
g->allgc = NULL;
g->finobj = NULL;
g->tobefnz = NULL;
+ g->sweepgc = g->sweepfin = NULL;
g->gray = g->grayagain = NULL;
g->weak = g->ephemeron = g->allweak = NULL;
g->totalbytes = sizeof(LG);
diff --git a/lstate.h b/lstate.h
index 85359fe3..302834ab 100644
--- a/lstate.h
+++ b/lstate.h
@@ -1,5 +1,5 @@
/*
-** $Id: lstate.h,v 2.77 2012/02/01 21:57:15 roberto Exp roberto $
+** $Id: lstate.h,v 2.78 2012/05/20 20:36:44 roberto Exp roberto $
** Global State
** See Copyright Notice in lua.h
*/
@@ -126,7 +126,8 @@ typedef struct global_State {
int sweepstrgc; /* position of sweep in `strt' */
GCObject *allgc; /* list of all collectable objects */
GCObject *finobj; /* list of collectable objects with finalizers */
- GCObject **sweepgc; /* current position of sweep */
+ GCObject **sweepgc; /* current position of sweep in list 'allgc' */
+ GCObject **sweepfin; /* current position of sweep in list 'finobj' */
GCObject *gray; /* list of gray objects */
GCObject *grayagain; /* list of objects to be traversed atomically */
GCObject *weak; /* list of tables with weak values */
--
cgit v1.2.3-55-g6feb