code review 5279048: runtime: faster and more scalable GC

src/pkg/runtime/mheap.c

 // Copyright 2009 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.
 
 // Page heap.
 //
 // See malloc.h for overview.
 //
 // When a MSpan is in the heap free list, state == MSpanFree
 // and heapmap(s->start) == span, heapmap(s->start+s->npages-1) == span.
@@ skipping 12 matching lines @@
 static MSpan *BestFit(MSpan*, uintptr, MSpan*);
 
 static void
 RecordSpan(void *vh, byte *p)
 {
         MHeap *h;
         MSpan *s;
 
         h = vh;
         s = (MSpan*)p;
-        s->allnext = h->allspans;
-        h->allspans = s;
+        //s->allnext = h->allspans;
+        //h->allspans = s;
+        if(h->nspan == nelem(h->allspans))
+                runtime·throw("span overflow");
+        h->allspans[h->nspan] = s;
+        h->nspan++;
 }
 
 // Initialize the heap; fetch memory using alloc.
 void
 runtime·MHeap_Init(MHeap *h, void *(*alloc)(uintptr))
 {
         uint32 i;
 
         runtime·FixAlloc_Init(&h->spanalloc, sizeof(MSpan), alloc, RecordSpan, h);
         runtime·FixAlloc_Init(&h->cachealloc, sizeof(MCache), alloc, nil, nil);
@@ skipping 323 matching lines @@
                 runtime·printf("failed MSpanList_Insert %p %p %p\n", span, span->next, span->prev);
                 runtime·throw("MSpanList_Insert");
         }
         span->next = list->next;
         span->prev = list;
         span->next->prev = span;
         span->prev->next = span;
 }