runtime: faster finalizers

Linux/amd64, 2 x Intel Xeon E5620, 8 HT cores, 2.40GHz
benchmark                    old ns/op    new ns/op    delta
BenchmarkFinalizer              420.00       261.00  -37.86%
BenchmarkFinalizer-2            985.00       201.00  -79.59%
BenchmarkFinalizer-4           1077.00       244.00  -77.34%
BenchmarkFinalizer-8           1155.00       180.00  -84.42%
BenchmarkFinalizer-16          1182.00       184.00  -84.43%

BenchmarkFinalizerRun          2128.00      1378.00  -35.24%
BenchmarkFinalizerRun-2        1655.00      1418.00  -14.32%
BenchmarkFinalizerRun-4        1634.00      1522.00   -6.85%
BenchmarkFinalizerRun-8        2213.00      1581.00  -28.56%
BenchmarkFinalizerRun-16       2424.00      1599.00  -34.03%

Darwin/amd64, Intel L9600, 2 cores, 2.13GHz
benchmark                    old ns/op    new ns/op    delta
BenchmarkChanCreation          1451.00       926.00  -36.18%
BenchmarkChanCreation-2        3124.00      1412.00  -54.80%
BenchmarkChanCreation-4        6121.00      2628.00  -57.07%

BenchmarkFinalizer              684.00       420.00  -38.60%
BenchmarkFinalizer-2          11195.00       398.00  -96.44%
BenchmarkFinalizer-4          15862.00       654.00  -95.88%

BenchmarkFinalizerRun          2025.00      1397.00  -31.01%
BenchmarkFinalizerRun-2        3920.00      1447.00  -63.09%
BenchmarkFinalizerRun-4        9471.00      1545.00  -83.69%

R=golang-dev, cw, rsc
CC=golang-dev
https://golang.org/cl/4963057

src/pkg/runtime/386/arch.h

 enum {
-	thechar = '8'
+	thechar = '8',
+	CacheLineSize = 64
 };

src/pkg/runtime/amd64/arch.h

 enum {
-	thechar = '6'
+	thechar = '6',
+	CacheLineSize = 64
 };

src/pkg/runtime/amd64/traceback.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 static uintptr isclosureentry(uintptr);

src/pkg/runtime/arm/arch.h

 enum {
-	thechar = '5'
+	thechar = '5',
+	CacheLineSize = 32
 };

src/pkg/runtime/arm/traceback.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 void runtime·deferproc(void);

src/pkg/runtime/cpuprof.c

@@ -49,6 +49,7 @@
 // in the situation when normally the goroutine "owns" handoff.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 enum

src/pkg/runtime/darwin/mem.c

+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 #include "runtime.h"
+#include "arch.h"
 #include "defs.h"
 #include "os.h"
 #include "malloc.h"

src/pkg/runtime/extern.go

@@ -131,8 +131,8 @@ func Semrelease(s *uint32)
 // The argument x must be a pointer to an object allocated by
 // calling new or by taking the address of a composite literal.
 // The argument f must be a function that takes a single argument
-// of x's type and returns no arguments.  If either of these is not
-// true, SetFinalizer aborts the program.
+// of x's type and can have arbitrary ignored return values.
+// If either of these is not true, SetFinalizer aborts the program.
 //
 // Finalizers are run in dependency order: if A points at B, both have
 // finalizers, and they are otherwise unreachable, only the finalizer
@@ -156,9 +156,6 @@ func Semrelease(s *uint32)
 // A single goroutine runs all finalizers for a program, sequentially.
 // If a finalizer must run for a long time, it should do so by starting
 // a new goroutine.
-//
-// TODO(rsc): allow f to have (ignored) return values
-//
 func SetFinalizer(x, f interface{})
 
 func getgoroot() string

src/pkg/runtime/freebsd/mem.c

+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 #include "runtime.h"
+#include "arch.h"
 #include "defs.h"
 #include "os.h"
 #include "malloc.h"

src/pkg/runtime/iface.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "type.h"
 #include "malloc.h"
 

src/pkg/runtime/linux/mem.c

+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 #include "runtime.h"
+#include "arch.h"
 #include "defs.h"
 #include "os.h"
 #include "malloc.h"

src/pkg/runtime/malloc.goc

@@ -8,6 +8,7 @@
 
 package runtime
 #include "runtime.h"
+#include "arch.h"
 #include "stack.h"
 #include "malloc.h"
 #include "defs.h"
@@ -85,7 +86,7 @@ runtime·mallocgc(uintptr size, uint32 flag, int32 dogc, int32 zeroed)
 				rate = 0x3fffffff;
 			m->mcache->next_sample = runtime·fastrand1() % (2*rate);
 		profile:
-			runtime·setblockspecial(v);
+			runtime·setblockspecial(v, true);
 			runtime·MProf_Malloc(v, size);
 		}
 	}
@@ -457,8 +458,7 @@ func SetFinalizer(obj Eface, finalizer Eface) {
 
 	if(obj.type == nil) {
 		runtime·printf("runtime.SetFinalizer: first argument is nil interface\n");
-	throw:
-		runtime·throw("runtime.SetFinalizer");
+		goto throw;
 	}
 	if(obj.type->kind != KindPtr) {
 		runtime·printf("runtime.SetFinalizer: first argument is %S, not pointer\n", *obj.type->string);
@@ -470,11 +470,8 @@ func SetFinalizer(obj Eface, finalizer Eface) {
 	}
 	nret = 0;
 	if(finalizer.type != nil) {
-		if(finalizer.type->kind != KindFunc) {
-		badfunc:
-			runtime·printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.type->string, *obj.type->string);
-			goto throw;
-		}
+		if(finalizer.type->kind != KindFunc)
+			goto badfunc;
 		ft = (FuncType*)finalizer.type;
 		if(ft->dotdotdot || ft->in.len != 1 || *(Type**)ft->in.array != obj.type)
 			goto badfunc;
@@ -486,11 +483,16 @@ func SetFinalizer(obj Eface, finalizer Eface) {
 			nret += t->size;
 		}
 		nret = (nret + sizeof(void*)-1) & ~(sizeof(void*)-1);
-
-		if(runtime·getfinalizer(obj.data, 0)) {
-			runtime·printf("runtime.SetFinalizer: finalizer already set\n");
-			goto throw;
-		}
 	}
-	runtime·addfinalizer(obj.data, finalizer.data, nret);
+	
+	if(!runtime·addfinalizer(obj.data, finalizer.data, nret)) {
+		runtime·printf("runtime.SetFinalizer: finalizer already set\n");
+		goto throw;
+	}
+	return;
+
+badfunc:
+	runtime·printf("runtime.SetFinalizer: second argument is %S, not func(%S)\n", *finalizer.type->string, *obj.type->string);
+throw:
+	runtime·throw("runtime.SetFinalizer");
 }

src/pkg/runtime/malloc.h

@@ -362,11 +362,11 @@ struct MHeap
 
 	// central free lists for small size classes.
 	// the union makes sure that the MCentrals are
-	// spaced 64 bytes apart, so that each MCentral.Lock
+	// spaced CacheLineSize bytes apart, so that each MCentral.Lock
 	// gets its own cache line.
 	union {
 		MCentral;
-		byte pad[64];
+		byte pad[CacheLineSize];
 	} central[NumSizeClasses];
 
 	FixAlloc spanalloc;	// allocator for Span*
@@ -394,7 +394,7 @@ int32	runtime·checking;
 void	runtime·markspan(void *v, uintptr size, uintptr n, bool leftover);
 void	runtime·unmarkspan(void *v, uintptr size);
 bool	runtime·blockspecial(void*);
-void	runtime·setblockspecial(void*);
+void	runtime·setblockspecial(void*, bool);
 void	runtime·purgecachedstats(M*);
 
 enum
@@ -419,13 +419,5 @@ enum {
 };
 extern int32 runtime·malloc_profile;
 
-typedef struct Finalizer Finalizer;
-struct Finalizer
-{
-	Finalizer *next;	// for use by caller of getfinalizer
-	void (*fn)(void*);
-	void *arg;
-	int32 nret;
-};
-
-Finalizer*	runtime·getfinalizer(void*, bool);
+bool	runtime·getfinalizer(void *p, bool del, void (**fn)(void*), int32 *nret);
+void	runtime·walkfintab(void (*fn)(void*));

src/pkg/runtime/mcache.c

@@ -7,6 +7,7 @@
 // See malloc.h for an overview.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 void*

src/pkg/runtime/mcentral.c

@@ -15,6 +15,7 @@
 // so that it is faster to move those lists between MCaches and MCentrals.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 static bool MCentral_Grow(MCentral *c);

src/pkg/runtime/mfinal.c

@@ -3,12 +3,17 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
-// Lock to protect finalizer data structures.
-// Cannot reuse mheap.Lock because the finalizer
-// maintenance requires allocation.
-static Lock finlock;
+enum { debug = 0 };
+
+typedef struct Fin Fin;
+struct Fin
+{
+	void (*fn)(void*);
+	int32 nret;
+};
 
 // Finalizer hash table.  Direct hash, linear scan, at most 3/4 full.
 // Table size is power of 3 so that hash can be key % max.
@@ -20,15 +25,24 @@ static Lock finlock;
 typedef struct Fintab Fintab;
 struct Fintab
 {
+	Lock;
 	void **key;
-	Finalizer **val;
+	Fin *val;
 	int32 nkey;	// number of non-nil entries in key
 	int32 ndead;	// number of dead (-1) entries in key
 	int32 max;	// size of key, val allocations
 };
 
+#define TABSZ 17
+#define TAB(p) (&fintab[((uintptr)(p)>>3)%TABSZ])
+
+static struct {
+	Fintab;
+	uint8 pad[CacheLineSize - sizeof(Fintab)];	
+} fintab[TABSZ];
+
 static void
-addfintab(Fintab *t, void *k, Finalizer *v)
+addfintab(Fintab *t, void *k, void (*fn)(void*), int32 nret)
 {
 	int32 i, j;
 
@@ -51,29 +65,31 @@ addfintab(Fintab *t, void *k, Finalizer *v)
 
 ret:
 	t->key[i] = k;
-	t->val[i] = v;
+	t->val[i].fn = fn;
+	t->val[i].nret = nret;
 }
 
-static Finalizer*
-lookfintab(Fintab *t, void *k, bool del)
+static bool
+lookfintab(Fintab *t, void *k, bool del, Fin *f)
 {
 	int32 i, j;
-	Finalizer *v;
 
 	if(t->max == 0)
-		return nil;
+		return false;
 	i = (uintptr)k % (uintptr)t->max;
 	for(j=0; j<t->max; j++) {
 		if(t->key[i] == nil)
-			return nil;
+			return false;
 		if(t->key[i] == k) {
-			v = t->val[i];
+			if(f)
+				*f = t->val[i];
 			if(del) {
 				t->key[i] = (void*)-1;
-				t->val[i] = nil;
+				t->val[i].fn = nil;
+				t->val[i].nret = 0;
 				t->ndead++;
 			}
-			return v;
+			return true;
 		}
 		if(++i == t->max)
 			i = 0;
@@ -81,88 +97,100 @@ lookfintab(Fintab *t, void *k, bool del)
 
 	// cannot happen - table is known to be non-full
 	runtime·throw("finalizer table inconsistent");
-	return nil;
+	return false;
 }
 
-static Fintab fintab;
-
-// add finalizer; caller is responsible for making sure not already in table
-void
-runtime·addfinalizer(void *p, void (*f)(void*), int32 nret)
+static void
+resizefintab(Fintab *tab)
 {
 	Fintab newtab;
+	void *k;
 	int32 i;
-	byte *base;
-	Finalizer *e;
+
+	runtime·memclr((byte*)&newtab, sizeof newtab);
+	newtab.max = tab->max;
+	if(newtab.max == 0)
+		newtab.max = 3*3*3;
+	else if(tab->ndead < tab->nkey/2) {
+		// grow table if not many dead values.
+		// otherwise just rehash into table of same size.
+		newtab.max *= 3;
+	}
 	
-	e = nil;
-	if(f != nil) {
-		e = runtime·mal(sizeof *e);
-		e->fn = f;
-		e->nret = nret;
+	newtab.key = runtime·mallocgc(newtab.max*sizeof newtab.key[0], FlagNoPointers, 0, 1);
+	newtab.val = runtime·mallocgc(newtab.max*sizeof newtab.val[0], 0, 0, 1);
+	
+	for(i=0; i<tab->max; i++) {
+		k = tab->key[i];
+		if(k != nil && k != (void*)-1)
+			addfintab(&newtab, k, tab->val[i].fn, tab->val[i].nret);
 	}
+	
+	runtime·free(tab->key);
+	runtime·free(tab->val);
+	
+	tab->key = newtab.key;
+	tab->val = newtab.val;
+	tab->nkey = newtab.nkey;
+	tab->ndead = newtab.ndead;
+	tab->max = newtab.max;
+}
 
-	runtime·lock(&finlock);
-	if(!runtime·mlookup(p, &base, nil, nil) || p != base) {
-		runtime·unlock(&finlock);
-		runtime·throw("addfinalizer on invalid pointer");
+bool
+runtime·addfinalizer(void *p, void (*f)(void*), int32 nret)
+{
+	Fintab *tab;
+	byte *base;
+	
+	if(debug) {
+		if(!runtime·mlookup(p, &base, nil, nil) || p != base)
+			runtime·throw("addfinalizer on invalid pointer");
 	}
+	
+	tab = TAB(p);
+	runtime·lock(tab);
 	if(f == nil) {
-		lookfintab(&fintab, p, 1);
-		runtime·unlock(&finlock);
-		return;
+		if(lookfintab(tab, p, true, nil))
+			runtime·setblockspecial(p, false);
+		runtime·unlock(tab);
+		return true;
 	}
 
-	if(lookfintab(&fintab, p, 0)) {
-		runtime·unlock(&finlock);
-		runtime·throw("double finalizer");
+	if(lookfintab(tab, p, false, nil)) {
+		runtime·unlock(tab);
+		return false;
 	}
-	runtime·setblockspecial(p);
 
-	if(fintab.nkey >= fintab.max/2+fintab.max/4) {
+	if(tab->nkey >= tab->max/2+tab->max/4) {
 		// keep table at most 3/4 full:
 		// allocate new table and rehash.
-
-		runtime·memclr((byte*)&newtab, sizeof newtab);
-		newtab.max = fintab.max;
-		if(newtab.max == 0)
-			newtab.max = 3*3*3;
-		else if(fintab.ndead < fintab.nkey/2) {
-			// grow table if not many dead values.
-			// otherwise just rehash into table of same size.
-			newtab.max *= 3;
-		}
-
-		newtab.key = runtime·mallocgc(newtab.max*sizeof newtab.key[0], FlagNoPointers, 0, 1);
-		newtab.val = runtime·mallocgc(newtab.max*sizeof newtab.val[0], 0, 0, 1);
-
-		for(i=0; i<fintab.max; i++) {
-			void *k;
-
-			k = fintab.key[i];
-			if(k != nil && k != (void*)-1)
-				addfintab(&newtab, k, fintab.val[i]);
-		}
-		runtime·free(fintab.key);
-		runtime·free(fintab.val);
-		fintab = newtab;
+		resizefintab(tab);
 	}
 
-	addfintab(&fintab, p, e);
-	runtime·unlock(&finlock);
+	addfintab(tab, p, f, nret);
+	runtime·setblockspecial(p, true);
+	runtime·unlock(tab);
+	return true;
 }
 
 // get finalizer; if del, delete finalizer.
-// caller is responsible for updating RefHasFinalizer bit.
-Finalizer*
-runtime·getfinalizer(void *p, bool del)
+// caller is responsible for updating RefHasFinalizer (special) bit.
+bool
+runtime·getfinalizer(void *p, bool del, void (**fn)(void*), int32 *nret)
 {
-	Finalizer *f;
+	Fintab *tab;
+	bool res;
+	Fin f;
 	
-	runtime·lock(&finlock);
-	f = lookfintab(&fintab, p, del);
-	runtime·unlock(&finlock);
-	return f;
+	tab = TAB(p);
+	runtime·lock(tab);
+	res = lookfintab(tab, p, del, &f);
+	runtime·unlock(tab);
+	if(res==false)
+		return false;
+	*fn = f.fn;
+	*nret = f.nret;
+	return true;
 }
 
 void
@@ -170,12 +198,15 @@ runtime·walkfintab(void (*fn)(void*))
 {
 	void **key;
 	void **ekey;
+	int32 i;
 
-	runtime·lock(&finlock);
-	key = fintab.key;
-	ekey = key + fintab.max;
-	for(; key < ekey; key++)
-		if(*key != nil && *key != ((void*)-1))
-			fn(*key);
-	runtime·unlock(&finlock);
+	for(i=0; i<TABSZ; i++) {
+		runtime·lock(&fintab[i]);
+		key = fintab[i].key;
+		ekey = key + fintab[i].max;
+		for(; key < ekey; key++)
+			if(*key != nil && *key != ((void*)-1))
+				fn(*key);
+		runtime·unlock(&fintab[i]);
+	}
 }

src/pkg/runtime/mfinal_test.go

+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"runtime"
+	"sync"
+	"sync/atomic"
+	"testing"
+)
+
+func fin(v *int) {
+}
+
+func BenchmarkFinalizer(b *testing.B) {
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	var wg sync.WaitGroup
+	wg.Add(procs)
+	for p := 0; p < procs; p++ {
+		go func() {
+			var data [CallsPerSched]*int
+			for i := 0; i < CallsPerSched; i++ {
+				data[i] = new(int)
+			}
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for i := 0; i < CallsPerSched; i++ {
+					runtime.SetFinalizer(data[i], fin)
+				}
+				for i := 0; i < CallsPerSched; i++ {
+					runtime.SetFinalizer(data[i], nil)
+				}
+			}
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}
+
+func BenchmarkFinalizerRun(b *testing.B) {
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	var wg sync.WaitGroup
+	wg.Add(procs)
+	for p := 0; p < procs; p++ {
+		go func() {
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for i := 0; i < CallsPerSched; i++ {
+					v := new(int)
+					runtime.SetFinalizer(v, fin)
+				}
+				runtime.GC()
+			}
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+}

src/pkg/runtime/mfixalloc.c

@@ -7,6 +7,7 @@
 // See malloc.h for overview.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 // Initialize f to allocate objects of the given size,

src/pkg/runtime/mgc0.c

@@ -5,6 +5,7 @@
 // Garbage collector.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 #include "stack.h"
 
@@ -67,12 +68,33 @@ struct Workbuf
 	byte *obj[512-2];
 };
 
+typedef struct Finalizer Finalizer;
+struct Finalizer
+{
+	void (*fn)(void*);
+	void *arg;
+	int32 nret;
+};
+
+typedef struct FinBlock FinBlock;
+struct FinBlock
+{
+	FinBlock *alllink;
+	FinBlock *next;
+	int32 cnt;
+	int32 cap;
+	Finalizer fin[1];
+};
+
 extern byte data[];
 extern byte etext[];
 extern byte end[];
 
 static G *fing;
-static Finalizer *finq;
+static FinBlock *finq; // list of finalizers that are to be executed
+static FinBlock *finc; // cache of free blocks
+static FinBlock *allfin; // list of all blocks
+static Lock finlock;
 static int32 fingwait;
 
 static void runfinq(void);
@@ -651,6 +673,7 @@ static void
 mark(void (*scan)(byte*, int64))
 {
 	G *gp;
+	FinBlock *fb;
 
 	// mark data+bss.
 	// skip runtime·mheap itself, which has no interesting pointers
@@ -685,11 +708,50 @@ mark(void (*scan)(byte*, int64))
 	else
 		runtime·walkfintab(markfin);
 
+	for(fb=allfin; fb; fb=fb->alllink)
+		scanblock((byte*)fb->fin, fb->cnt*sizeof(fb->fin[0]));
+
 	// in multiproc mode, join in the queued work.
 	scan(nil, 0);
 }
 
-// Sweep frees or calls finalizers for blocks not marked in the mark phase.
+static bool
+handlespecial(byte *p, uintptr size)
+{
+	void (*fn)(void*);
+	int32 nret;
+	FinBlock *block;
+	Finalizer *f;
+	
+	if(!runtime·getfinalizer(p, true, &fn, &nret)) {
+		runtime·setblockspecial(p, false);
+		runtime·MProf_Free(p, size);
+		return false;
+	}
+
+	runtime·lock(&finlock);
+	if(finq == nil || finq->cnt == finq->cap) {
+		if(finc == nil) {
+			finc = runtime·SysAlloc(PageSize);
+			finc->cap = (PageSize - sizeof(FinBlock)) / sizeof(Finalizer) + 1;
+			finc->alllink = allfin;
+			allfin = finc;
+		}
+		block = finc;
+		finc = block->next;
+		block->next = finq;
+		finq = block;
+	}
+	f = &finq->fin[finq->cnt];
+	finq->cnt++;
+	f->fn = fn;
+	f->nret = nret;
+	f->arg = p;
+	runtime·unlock(&finlock); 
+	return true;
+}
+
+// Sweep frees or collects finalizers for blocks not marked in the mark phase.
 // It clears the mark bits in preparation for the next GC round.
 static void
 sweep(void)
@@ -699,7 +761,6 @@ sweep(void)
 	uintptr size;
 	byte *p;
 	MCache *c;
-	Finalizer *f;
 	byte *arena_start;
 
 	arena_start = runtime·mheap.arena_start;
@@ -750,21 +811,12 @@ sweep(void)
 				continue;
 			}
 
+			// Special means it has a finalizer or is being profiled.
+			// In DebugMark mode, the bit has been coopted so
+			// we have to assume all blocks are special.
 			if(DebugMark || (bits & bitSpecial) != 0) {
-				// Special means it has a finalizer or is being profiled.
-				// In DebugMark mode, the bit has been coopted so
-				// we have to assume all blocks are special.
-				f = runtime·getfinalizer(p, 1);
-				if(f != nil) {
-					f->arg = p;
-					for(;;) {
-						f->next = finq;
-						if(runtime·casp(&finq, f->next, f))
-							break;
-					}
+				if(handlespecial(p, size))
 					continue;
-				}
-				runtime·MProf_Free(p, size);
 			}
 
 			// Mark freed; restore block boundary bit.
@@ -864,7 +916,6 @@ runtime·gc(int32 force)
 	int64 t0, t1, t2, t3;
 	uint64 heap0, heap1, obj0, obj1;
 	byte *p;
-	Finalizer *fp;
 	bool extra;
 
 	// The gc is turned off (via enablegc) until
@@ -945,8 +996,7 @@ runtime·gc(int32 force)
 	m->gcing = 0;
 
 	m->locks++;	// disable gc during the mallocs in newproc
-	fp = finq;
-	if(fp != nil) {
+	if(finq != nil) {
 		// kick off or wake up goroutine to run queued finalizers
 		if(fing == nil)
 			fing = runtime·newproc1((byte*)runfinq, nil, 0, 0, runtime·gc);
@@ -987,8 +1037,8 @@ runtime·gc(int32 force)
 	// the maximum number of procs.
 	runtime·starttheworld(extra);
 
-	// give the queued finalizers, if any, a chance to run
-	if(fp != nil)
+	// give the queued finalizers, if any, a chance to run	
+	if(finq != nil)	
 		runtime·gosched();
 
 	if(gctrace > 1 && !force)
@@ -1014,9 +1064,13 @@ runtime·UpdateMemStats(void)
 static void
 runfinq(void)
 {
-	Finalizer *f, *next;
+	Finalizer *f;
+	FinBlock *fb, *next;
 	byte *frame;
+	uint32 framesz, framecap, i;
 
+	frame = nil;
+	framecap = 0;
 	for(;;) {
 		// There's no need for a lock in this section
 		// because it only conflicts with the garbage
@@ -1024,25 +1078,34 @@ runfinq(void)
 		// runs when everyone else is stopped, and
 		// runfinq only stops at the gosched() or
 		// during the calls in the for loop.
-		f = finq;
+		fb = finq;
 		finq = nil;
-		if(f == nil) {
+		if(fb == nil) {
 			fingwait = 1;
 			g->status = Gwaiting;
 			g->waitreason = "finalizer wait";
 			runtime·gosched();
 			continue;
 		}
-		for(; f; f=next) {
-			next = f->next;
-			frame = runtime·mal(sizeof(uintptr) + f->nret);
-			*(void**)frame = f->arg;
-			reflect·call((byte*)f->fn, frame, sizeof(uintptr) + f->nret);
-			runtime·free(frame);
-			f->fn = nil;
-			f->arg = nil;
-			f->next = nil;
-			runtime·free(f);
+		for(; fb; fb=next) {
+			next = fb->next;
+			for(i=0; i<fb->cnt; i++) {
+				f = &fb->fin[i];
+				framesz = sizeof(uintptr) + f->nret;
+				if(framecap < framesz) {
+					runtime·free(frame);
+					frame = runtime·mal(framesz);
+					framecap = framesz;
+				}
+				*(void**)frame = f->arg;
+				runtime·setblockspecial(f->arg, false);
+				reflect·call((byte*)f->fn, frame, sizeof(uintptr) + f->nret);
+				f->fn = nil;
+				f->arg = nil;
+			}
+			fb->cnt = 0;
+			fb->next = finc;
+			finc = fb;
 		}
 		runtime·gc(1);	// trigger another gc to clean up the finalized objects, if possible
 	}
@@ -1203,7 +1266,7 @@ runtime·blockspecial(void *v)
 }
 
 void
-runtime·setblockspecial(void *v)
+runtime·setblockspecial(void *v, bool s)
 {
 	uintptr *b, off, shift, bits, obits;
 
@@ -1216,7 +1279,10 @@ runtime·setblockspecial(void *v)
 
 	for(;;) {
 		obits = *b;
-		bits = obits | (bitSpecial<<shift);
+		if(s)
+			bits = obits | (bitSpecial<<shift);
+		else
+			bits = obits & ~(bitSpecial<<shift);
 		if(runtime·singleproc) {
 			*b = bits;
 			break;

src/pkg/runtime/mheap.c

@@ -13,6 +13,7 @@
 // and heapmap(i) == span for all s->start <= i < s->start+s->npages.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 static MSpan *MHeap_AllocLocked(MHeap*, uintptr, int32);

src/pkg/runtime/mprof.goc

@@ -7,6 +7,7 @@
 
 package runtime
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 #include "defs.h"
 #include "type.h"

src/pkg/runtime/msize.c

@@ -26,6 +26,7 @@
 // TODO(rsc): Compute max waste for any given size.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 int32 runtime·class_to_size[NumSizeClasses];

src/pkg/runtime/openbsd/mem.c

+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 #include "runtime.h"
+#include "arch.h"
 #include "defs.h"
 #include "os.h"
 #include "malloc.h"

src/pkg/runtime/openbsd/os.h

+// Copyright 2010 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
 #define SIG_DFL ((void*)0)
 #define SIG_IGN ((void*)1)
 

src/pkg/runtime/plan9/mem.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 #include "os.h"
 

src/pkg/runtime/runtime.h

@@ -490,8 +490,7 @@ uintptr	runtime·nohash(uint32, void*);
 uint32	runtime·noequal(uint32, void*, void*);
 void*	runtime·malloc(uintptr size);
 void	runtime·free(void *v);
-void	runtime·addfinalizer(void*, void(*fn)(void*), int32);
-void	runtime·walkfintab(void (*fn)(void*));
+bool	runtime·addfinalizer(void*, void(*fn)(void*), int32);
 void	runtime·runpanic(Panic*);
 void*	runtime·getcallersp(void*);
 int32	runtime·mcount(void);

src/pkg/runtime/sema.goc

@@ -19,6 +19,7 @@
 
 package runtime
 #include "runtime.h"
+#include "arch.h"
 
 typedef struct Sema Sema;
 struct Sema
@@ -45,11 +46,7 @@ struct SemaRoot
 static union
 {
 	SemaRoot;
-	// Modern processors tend to have 64-byte cache lines,
-	// potentially with 128-byte effective cache line size for reading.
-	// While there are hypothetical architectures
-	// with 16-4096 byte cache lines, 128 looks like a good compromise.
-	uint8 pad[128];
+	uint8 pad[CacheLineSize];
 } semtable[SEMTABLESZ];
 
 static SemaRoot*

src/pkg/runtime/slice.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "type.h"
 #include "malloc.h"
 

src/pkg/runtime/string.goc

@@ -4,6 +4,7 @@
 
 package runtime
 #include "runtime.h"
+#include "arch.h"
 #include "malloc.h"
 
 String	runtime·emptystring;

src/pkg/runtime/windows/mem.c

@@ -3,6 +3,7 @@
 // license that can be found in the LICENSE file.
 
 #include "runtime.h"
+#include "arch.h"
 #include "os.h"
 #include "defs.h"
 #include "malloc.h"

test/mallocfin.go

@@ -47,18 +47,28 @@ func finalB(b *B) {
 	nfinal++
 }
 
+func nofinalB(b *B) {
+	panic("nofinalB run")
+}
+
 func main() {
 	runtime.GOMAXPROCS(4)
 	for i = 0; i < N; i++ {
 		b := &B{i}
 		a := &A{b, i}
+		c := new(B)
+		runtime.SetFinalizer(c, nofinalB)
 		runtime.SetFinalizer(b, finalB)
 		runtime.SetFinalizer(a, finalA)
+		runtime.SetFinalizer(c, nil)
 	}
 	for i := 0; i < N; i++ {
 		runtime.GC()
 		runtime.Gosched()
 		time.Sleep(1e6)
+		if nfinal >= N*8/10 {
+			break
+		}
 	}
 	if nfinal < N*8/10 {
 		println("not enough finalizing:", nfinal, "/", N)

test/mallocrep.go

@@ -33,6 +33,7 @@ func bigger() {
 
 func main() {
 	runtime.GC()               // clean up garbage from init
+	runtime.UpdateMemStats()   // first call can do some allocations
 	runtime.MemProfileRate = 0 // disable profiler
 	runtime.MemStats.Alloc = 0 // ignore stacks
 	flag.Parse()