Safepointing in GC

runtime/vm/scavenger.cc

Index: runtime/vm/scavenger.cc
diff --git a/runtime/vm/scavenger.cc b/runtime/vm/scavenger.cc
index eac850151aaafdfdb4c42bae5dce5a2b99e2940a..4da52556c564fab6440c3d33c797ae063b07e854 100644
--- a/runtime/vm/scavenger.cc
+++ b/runtime/vm/scavenger.cc
@@ -16,6 +16,7 @@
 #include "vm/object_id_ring.h"
 #include "vm/stack_frame.h"
 #include "vm/store_buffer.h"
+#include "vm/thread_registry.h"
 #include "vm/verified_memory.h"
 #include "vm/verifier.h"
 #include "vm/visitor.h"
@@ -803,6 +804,8 @@ void Scavenger::Scavenge(bool invoke_api_callbacks) {
   ASSERT(!scavenging_);
   scavenging_ = true;
   Isolate* isolate = heap_->isolate();
+  // TODO(koda): Allow concurrent sweeper to keep running.
+  isolate->thread_registry()->SafepointThreads();
   PageSpace* page_space = heap_->old_space();
   NoSafepointScope no_safepoints;
 
@@ -858,6 +861,8 @@ void Scavenger::Scavenge(bool invoke_api_callbacks) {
     OS::PrintErr(" done.\n");
   }
 
+  isolate->thread_registry()->ResumeAllThreads();
+
   // Done scavenging. Reset the marker.
   ASSERT(scavenging_);
   scavenging_ = false;