If we can't rehash the backing store for weak sets & maps, do a last resort GC

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 9f7524ccefb7a4dc85ae9ee1677840b14e8d1bad..c8892c6e9a84ac1da892fb15adc9b14c5893055d 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -17747,6 +17747,17 @@ Handle<ObjectHashTable> ObjectHashTable::Put(Handle<ObjectHashTable> table,
   if ((table->NumberOfDeletedElements() << 1) > table->NumberOfElements()) {
     table->Rehash(isolate->factory()->undefined_value());
   }
+  // If we're out of luck, we didn't get a GC recently, and so rehashing
+  // isn't enough to avoid a crash.
+  int nof = table->NumberOfElements() + 1;
+  if (!table->HasSufficientCapacity(nof)) {
+    int capacity = ObjectHashTable::ComputeCapacity(nof * 2);
+    if (capacity > ObjectHashTable::kMaxCapacity) {
+      isolate->heap()->CollectAllAvailableGarbage(

[Hannes Payer (out of office), 2016/07/07 14:26:45]

I am not happy with this CL since it adds another dependency from runtime to GC.
However, I do not see a better solution right now. The HashTable is like the
heap, you have to do GC on OOM.

Can you call CollectGarbage two times instead of CollectAllAvailableGarbage?
This would result in less heavy GCs.

+          "last resort gc (object hash table)");
+      table->Rehash(isolate->factory()->undefined_value());
+    }
+  }
 
   // Check whether the hash table should be extended.
   table = EnsureCapacity(table, 1, key);