Parallel and concurrent sweeping.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index b3cfb4327db2085b1f0934de8240e9f101de2e5e..3babbc4b69b5e2b3293ef1adce04f01ef9bcdb65 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -42,6 +42,7 @@
 #include "hashmap.h"
 #include "heap.h"
 #include "optimizing-compiler-thread.h"
+#include "sweeper-thread.h"
 #include "regexp-stack.h"
 #include "runtime-profiler.h"
 #include "runtime.h"
@@ -1070,6 +1071,10 @@ class Isolate {
     return &optimizing_compiler_thread_;
   }
 
+  SweeperThread** sweeper_threads() {
+    return sweeper_thread_;
+  }
+
  private:
   Isolate();
 
@@ -1295,11 +1300,13 @@ class Isolate {
 
   DeferredHandles* deferred_handles_head_;
   OptimizingCompilerThread optimizing_compiler_thread_;
+  SweeperThread** sweeper_thread_;
 
   friend class ExecutionAccess;
   friend class HandleScopeImplementer;
   friend class IsolateInitializer;
   friend class OptimizingCompilerThread;
+  friend class SweeperThread;
   friend class ThreadManager;
   friend class Simulator;
   friend class StackGuard;