Never access V8 from within Ruby GC.

ext/v8/v8_handle.cpp

@@ -10,13 +10,11 @@ v8_handle::v8_handle(Handle<void> handle) : handle(Persistent<void>::New(handle)
   this->dead = false;
 }
 
-v8_handle::~v8_handle() {
+v8_handle::~v8_handle() {}
-  handle.Dispose();
-  handle.Clear();
-  dead = true;
-}
 
 namespace {
+  VALUE handle_queue;
+
   void v8_handle_mark(v8_handle* handle) {
     rb_gc_mark(handle->weakref_callback);
     rb_gc_mark(handle->weakref_callback_parameters);
@@ -26,6 +24,21 @@ namespace {
     delete handle;
   }
 
+  void v8_handle_enqueue(v8_handle* handle) {
+    handle->dead = true;
+    VALUE zombie = Data_Wrap_Struct(rr_v8_handle_class(), 0, v8_handle_free, handle);
+    rb_ary_unshift(handle_queue, zombie);
+  }
+
+  void v8_handle_dequeue(GCType type, GCCallbackFlags flags) {
+    for (VALUE handle = rb_ary_pop(handle_queue); RTEST(handle); handle = rb_ary_pop(handle_queue)) {
+      v8_handle* dead = NULL;
+      Data_Get_Struct(handle, struct v8_handle, dead);
+      dead->handle.Dispose();
+      dead->handle.Clear();
+    }
+  }
+
   VALUE New(VALUE self, VALUE handle) {
     if (RTEST(handle)) {
       Persistent<void> that = rr_v8_handle<void>(handle);
@@ -101,11 +114,15 @@ void rr_init_handle() {
   rr_define_method(HandleClass, "ClearWeak", ClearWeak, 0);
   rr_define_method(HandleClass, "IsNearDeath", IsNearDeath, 0);
   rr_define_method(HandleClass, "IsWeak", IsWeak, 0);
+
+  handle_queue = rb_ary_new();
+  rb_gc_register_address(&handle_queue);
+  V8::AddGCPrologueCallback(v8_handle_dequeue);
 }
 
 VALUE rr_v8_handle_new(VALUE klass, v8::Handle<void> handle) {
   v8_handle* new_handle = new v8_handle(handle);
-  return Data_Wrap_Struct(klass, v8_handle_mark, v8_handle_free, new_handle);
+  return Data_Wrap_Struct(klass, v8_handle_mark, v8_handle_enqueue, new_handle);
 }
 
 VALUE rr_v8_handle_class() {

ext/v8/v8_locker.cpp

@@ -66,8 +66,8 @@ namespace {
     * For details on V8 locking semantics, see the locking {API http://izs.me/v8-docs/classv8_1_1Unlocker.html}
     * @return [V8::C::Unocker] the new locker
     */
-    VALUE New(VALUE UnockerClass) {
+    VALUE New(VALUE UnlockerClass) {
-      Unlocker unlocker = new Unlocker();
+      Unlocker* unlocker = new Unlocker();
       return Data_Wrap_Struct(UnlockerClass, 0, 0, (void*)unlocker);
     }
 
@@ -80,7 +80,7 @@ namespace {
     */
     VALUE Delete(VALUE self) {
       Unlocker* unlocker;
-      Data_Get_Struct(self, class Locker, locker);
+      Data_Get_Struct(self, class Unlocker, unlocker);
       delete unlocker;
     }
   }
@@ -126,7 +126,6 @@ namespace {
 }
 
 void rr_init_v8_locker() {
-  VALUE V8 = rb_define_module("V8");
   VALUE LockerClass = rr_define_class("Locker");
   VALUE UnlockerClass = rr_define_class("Unlocker");
   rr_define_singleton_method(LockerClass, "new", Lock::New, 0);

lib/v8.rb

@@ -4,6 +4,7 @@ $:.unshift(File.dirname(__FILE__)) unless
 module V8
   require 'v8/version'
   require 'v8/v8' #native glue
+  require 'v8/c/locker'
   require 'v8/portal'
   require 'v8/portal/caller'
   require 'v8/portal/proxies'

lib/v8/portal/proxies.rb

@@ -43,7 +43,6 @@ module V8
         @js_proxies_js2rb[proxy] = target
         @js_proxies_rb2js[target] = proxy
         proxy.MakeWeak(nil, @clear_js_proxy)
-        V8::C::V8::AdjustAmountOfExternalAllocatedMemory(16 * 1024)
       end
 
       # Lookup the JavaScript proxy for a natively Ruby object
@@ -66,7 +65,6 @@ module V8
         @rb_proxies_rb2js[proxy.object_id] = target
         @rb_proxies_js2rb[target] = proxy.object_id
         ObjectSpace.define_finalizer(proxy, @clear_rb_proxy)
-        V8::C::V8::AdjustAmountOfExternalAllocatedMemory(8 * 1024)
       end
 
       # Looks up the Ruby proxy for an object that is natively JavaScript
@@ -115,7 +113,6 @@ module V8
           rb = @js2rb[proxy]
           @js2rb.delete(proxy)
           @rb2js.delete(rb)
-          V8::C::V8::AdjustAmountOfExternalAllocatedMemory(-16 * 1024)
         end
       end
 
@@ -146,7 +143,6 @@ module V8
           if js = @rb2js[proxy_id]
             @rb2js.delete(proxy_id)
             @js2rb.delete(js)
-            V8::C::V8::AdjustAmountOfExternalAllocatedMemory(-8 * 1024)
           end
         end
       end

specthread/spec_helper.rb

@@ -0,0 +1,2 @@
+require Pathname(__FILE__).dirname.join('../spec/spec_helper')
+

specthread/threading_spec.rb

@@ -0,0 +1,13 @@
+
+require 'spec_helper'
+
+describe "using v8 from multiple threads" do
+  
+  it "is possible" do
+    Thread.new do
+      require 'v8'
+      V8::Context.new
+    end.join
+    V8::Context.new
+  end
+end