Allocate optimizing compiler thread only when necessary.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 6eb29606d4a3cb4447db98125d239d8f8c8a3b50..5a80d3dd7d1d6a5a75222cf4bfbb478f1f94f376 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -1803,7 +1803,7 @@ Isolate::Isolate()
       heap_profiler_(NULL),
       function_entry_hook_(NULL),
       deferred_handles_head_(NULL),
-      optimizing_compiler_thread_(this),
+      optimizing_compiler_thread_(NULL),
       marking_thread_(NULL),
       sweeper_thread_(NULL),
       stress_deopt_count_(0) {
@@ -1898,7 +1898,10 @@ void Isolate::Deinit() {
     debugger()->UnloadDebugger();
 #endif
 
-    if (FLAG_concurrent_recompilation) optimizing_compiler_thread_.Stop();
+    if (FLAG_concurrent_recompilation) {
+      optimizing_compiler_thread_->Stop();
+      delete optimizing_compiler_thread_;
+    }
 
     if (FLAG_sweeper_threads > 0) {
       for (int i = 0; i < FLAG_sweeper_threads; i++) {
@@ -2240,6 +2243,11 @@ bool Isolate::Init(Deserializer* des) {
 
   deoptimizer_data_ = new DeoptimizerData(memory_allocator_);
 
+  if (FLAG_concurrent_recompilation) {
+    optimizing_compiler_thread_ = new OptimizingCompilerThread(this);
+    optimizing_compiler_thread_->Start();
+  }
+
   const bool create_heap_objects = (des == NULL);
   if (create_heap_objects && !heap_.CreateHeapObjects()) {
     V8::FatalProcessOutOfMemory("heap object creation");
@@ -2346,8 +2354,6 @@ bool Isolate::Init(Deserializer* des) {
     FastNewClosureStub::InstallDescriptors(this);
   }
 
-  if (FLAG_concurrent_recompilation) optimizing_compiler_thread_.Start();
-
   if (FLAG_marking_threads > 0) {
     marking_thread_ = new MarkingThread*[FLAG_marking_threads];
     for (int i = 0; i < FLAG_marking_threads; i++) {