Run Crankshaft on a separate thread.

src/v8.cc

Index: src/v8.cc
diff --git a/src/v8.cc b/src/v8.cc
index 2910a0700d92223521dddf8a072fc65fb6fa9615..63b00de330a2d7b5bb46e3bdf18ad910f987e57c 100644
--- a/src/v8.cc
+++ b/src/v8.cc
@@ -31,6 +31,7 @@
 #include "isolate.h"
 #include "elements.h"
 #include "bootstrapper.h"
+#include "crankshaft-thread.h"
 #include "debug.h"
 #include "deoptimizer.h"
 #include "frames.h"
@@ -106,12 +107,24 @@ void V8::TearDown() {
 
   if (!has_been_set_up_ || has_been_disposed_) return;
 
-  ElementsAccessor::TearDown();
-  LOperand::TearDownCaches();
-  RegisteredExtension::UnregisterAll();
-
-  isolate->TearDown();
-  delete isolate;
+  if (FLAG_concurrent_crankshaft) {
+    // Lock only when required.
+    bool to_lock = !isolate->thread_manager()->IsLockedByCurrentThread();
+    if (to_lock)
+      isolate->thread_manager()->Lock();
+    isolate->TearDown();
+    // The crankshaft thread will tear down ElementsAccessor, LOperand
+    // and RegisteredExtension once it is safe to do so.
+    if (to_lock)
+      isolate->thread_manager()->Unlock();
+    CrankshaftThread::StopThread();
+  } else {
+    ElementsAccessor::TearDown();

[danno, 2012/05/22 10:32:19]

Yikes, this tear down work should always happen here, even when the crankshaft
thread is active... even if it requires some sort of synchronization.

+    LOperand::TearDownCaches();
+    RegisteredExtension::UnregisterAll();
+    isolate->TearDown();
+    delete isolate;
+  }
 
   is_running_ = false;
   has_been_disposed_ = true;
@@ -252,6 +265,9 @@ Object* V8::FillHeapNumberWithRandom(Object* heap_number,
 void V8::InitializeOncePerProcessImpl() {
   OS::SetUp();
 
+  if (i::FLAG_concurrent_crankshaft)

[danno, 2012/05/22 10:32:19]

nit: Always use { } even around single line statements:

if (i::FLAG_concurrent_crankshaft) {
  i::CrankshaftThread::StartThread();
}

+    i::CrankshaftThread::StartThread();
+
   use_crankshaft_ = FLAG_crankshaft;
 
   if (Serializer::enabled()) {