test/cctest/test-lockers.cc

// Copyright 2007-2011 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
//       copyright notice, this list of conditions and the following
//       disclaimer in the documentation and/or other materials provided
//       with the distribution.
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//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <limits.h>

#include "src/v8.h"

#include "src/api.h"
#include "src/base/platform/platform.h"
#include "src/base/smart-pointers.h"
#include "src/compilation-cache.h"
#include "src/execution.h"
#include "src/isolate.h"
#include "src/parsing/parser.h"
#include "src/unicode-inl.h"
#include "src/utils.h"
#include "test/cctest/cctest.h"

using ::v8::Context;
using ::v8::Extension;
using ::v8::Function;
using ::v8::HandleScope;
using ::v8::Local;
using ::v8::Object;
using ::v8::ObjectTemplate;
using ::v8::Persistent;
using ::v8::Script;
using ::v8::String;
using ::v8::Value;
using ::v8::V8;


// Migrating an isolate
class KangarooThread : public v8::base::Thread {
 public:
  KangarooThread(v8::Isolate* isolate, v8::Local<v8::Context> context)
      : Thread(Options("KangarooThread")),
        isolate_(isolate),
        context_(isolate, context) {}

  void Run() {
    {
      v8::Locker locker(isolate_);
      v8::Isolate::Scope isolate_scope(isolate_);
      CHECK_EQ(isolate_, v8::Isolate::GetCurrent());
      v8::HandleScope scope(isolate_);
      v8::Local<v8::Context> context =
          v8::Local<v8::Context>::New(isolate_, context_);
      v8::Context::Scope context_scope(context);
      Local<Value> v = CompileRun("getValue()");
      CHECK(v->IsNumber());
      CHECK_EQ(30, static_cast<int>(v->NumberValue(context).FromJust()));
    }
    {
      v8::Locker locker(isolate_);
      v8::Isolate::Scope isolate_scope(isolate_);
      v8::HandleScope scope(isolate_);
      v8::Local<v8::Context> context =
          v8::Local<v8::Context>::New(isolate_, context_);
      v8::Context::Scope context_scope(context);
      Local<Value> v = CompileRun("getValue()");
      CHECK(v->IsNumber());
      CHECK_EQ(30, static_cast<int>(v->NumberValue(context).FromJust()));
    }
    isolate_->Dispose();
  }

 private:
  v8::Isolate* isolate_;
  Persistent<v8::Context> context_;
};


// Migrates an isolate from one thread to another
TEST(KangarooIsolates) {
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  v8::base::SmartPointer<KangarooThread> thread1;
  {
    v8::Locker locker(isolate);
    v8::Isolate::Scope isolate_scope(isolate);
    v8::HandleScope handle_scope(isolate);
    v8::Local<v8::Context> context = v8::Context::New(isolate);
    v8::Context::Scope context_scope(context);
    CHECK_EQ(isolate, v8::Isolate::GetCurrent());
    CompileRun("function getValue() { return 30; }");
    thread1.Reset(new KangarooThread(isolate, context));
  }
  thread1->Start();
  thread1->Join();
}


static void CalcFibAndCheck(v8::Local<v8::Context> context) {
  Local<Value> v = CompileRun("function fib(n) {"
                              "  if (n <= 2) return 1;"
                              "  return fib(n-1) + fib(n-2);"
                              "}"
                              "fib(10)");
  CHECK(v->IsNumber());
  CHECK_EQ(55, static_cast<int>(v->NumberValue(context).FromJust()));
}

class JoinableThread {
 public:
  explicit JoinableThread(const char* name)
    : name_(name),
      semaphore_(0),
      thread_(this) {
  }

  virtual ~JoinableThread() {}

  void Start() {
    thread_.Start();
  }

  void Join() {
    semaphore_.Wait();
    thread_.Join();
  }

  virtual void Run() = 0;

 private:
  class ThreadWithSemaphore : public v8::base::Thread {
   public:
    explicit ThreadWithSemaphore(JoinableThread* joinable_thread)
        : Thread(Options(joinable_thread->name_)),
          joinable_thread_(joinable_thread) {}

    virtual void Run() {
      joinable_thread_->Run();
      joinable_thread_->semaphore_.Signal();
    }

   private:
    JoinableThread* joinable_thread_;
  };

  const char* name_;
  v8::base::Semaphore semaphore_;
  ThreadWithSemaphore thread_;

  friend class ThreadWithSemaphore;

  DISALLOW_COPY_AND_ASSIGN(JoinableThread);
};


class IsolateLockingThreadWithLocalContext : public JoinableThread {
 public:
  explicit IsolateLockingThreadWithLocalContext(v8::Isolate* isolate)
    : JoinableThread("IsolateLockingThread"),
      isolate_(isolate) {
  }

  virtual void Run() {
    v8::Locker locker(isolate_);
    v8::Isolate::Scope isolate_scope(isolate_);
    v8::HandleScope handle_scope(isolate_);
    LocalContext local_context(isolate_);
    CHECK_EQ(isolate_, v8::Isolate::GetCurrent());
    CalcFibAndCheck(local_context.local());
  }
 private:
  v8::Isolate* isolate_;
};


static void StartJoinAndDeleteThreads(const i::List<JoinableThread*>& threads) {
  for (int i = 0; i < threads.length(); i++) {
    threads[i]->Start();
  }
  for (int i = 0; i < threads.length(); i++) {
    threads[i]->Join();
  }
  for (int i = 0; i < threads.length(); i++) {
    delete threads[i];
  }
}


// Run many threads all locking on the same isolate
TEST(IsolateLockingStress) {
  i::FLAG_always_opt = false;
#if V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  i::List<JoinableThread*> threads(kNThreads);
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  for (int i = 0; i < kNThreads; i++) {
    threads.Add(new IsolateLockingThreadWithLocalContext(isolate));
  }
  StartJoinAndDeleteThreads(threads);
  isolate->Dispose();
}


class IsolateNestedLockingThread : public JoinableThread {
 public:
  explicit IsolateNestedLockingThread(v8::Isolate* isolate)
    : JoinableThread("IsolateNestedLocking"), isolate_(isolate) {
  }
  virtual void Run() {
    v8::Locker lock(isolate_);
    v8::Isolate::Scope isolate_scope(isolate_);
    v8::HandleScope handle_scope(isolate_);
    LocalContext local_context(isolate_);
    {
      v8::Locker another_lock(isolate_);
      CalcFibAndCheck(local_context.local());
    }
    {
      v8::Locker another_lock(isolate_);
      CalcFibAndCheck(local_context.local());
    }
  }
 private:
  v8::Isolate* isolate_;
};


// Run  many threads with nested locks
TEST(IsolateNestedLocking) {
  i::FLAG_always_opt = false;
#if V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  i::List<JoinableThread*> threads(kNThreads);
  for (int i = 0; i < kNThreads; i++) {
    threads.Add(new IsolateNestedLockingThread(isolate));
  }
  StartJoinAndDeleteThreads(threads);
  isolate->Dispose();
}


class SeparateIsolatesLocksNonexclusiveThread : public JoinableThread {
 public:
  SeparateIsolatesLocksNonexclusiveThread(v8::Isolate* isolate1,
                                          v8::Isolate* isolate2)
    : JoinableThread("SeparateIsolatesLocksNonexclusiveThread"),
      isolate1_(isolate1), isolate2_(isolate2) {
  }

  virtual void Run() {
    v8::Locker lock(isolate1_);
    v8::Isolate::Scope isolate_scope(isolate1_);
    v8::HandleScope handle_scope(isolate1_);
    LocalContext local_context(isolate1_);

    IsolateLockingThreadWithLocalContext threadB(isolate2_);
    threadB.Start();
    CalcFibAndCheck(local_context.local());
    threadB.Join();
  }
 private:
  v8::Isolate* isolate1_;
  v8::Isolate* isolate2_;
};


// Run parallel threads that lock and access different isolates in parallel
TEST(SeparateIsolatesLocksNonexclusive) {
  i::FLAG_always_opt = false;
#if V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate1 = v8::Isolate::New(create_params);
  v8::Isolate* isolate2 = v8::Isolate::New(create_params);
  i::List<JoinableThread*> threads(kNThreads);
  for (int i = 0; i < kNThreads; i++) {
    threads.Add(new SeparateIsolatesLocksNonexclusiveThread(isolate1,
                                                             isolate2));
  }
  StartJoinAndDeleteThreads(threads);
  isolate2->Dispose();
  isolate1->Dispose();
}

class LockIsolateAndCalculateFibSharedContextThread : public JoinableThread {
 public:
  explicit LockIsolateAndCalculateFibSharedContextThread(
      v8::Isolate* isolate, v8::Local<v8::Context> context)
      : JoinableThread("LockIsolateAndCalculateFibThread"),
        isolate_(isolate),
        context_(isolate, context) {}

  virtual void Run() {
    v8::Locker lock(isolate_);
    v8::Isolate::Scope isolate_scope(isolate_);
    HandleScope handle_scope(isolate_);
    v8::Local<v8::Context> context =
        v8::Local<v8::Context>::New(isolate_, context_);
    v8::Context::Scope context_scope(context);
    CalcFibAndCheck(context);
  }
 private:
  v8::Isolate* isolate_;
  Persistent<v8::Context> context_;
};

class LockerUnlockerThread : public JoinableThread {
 public:
  explicit LockerUnlockerThread(v8::Isolate* isolate)
    : JoinableThread("LockerUnlockerThread"),
      isolate_(isolate) {
  }

  virtual void Run() {
    isolate_->DiscardThreadSpecificMetadata();  // No-op
    {
      v8::Locker lock(isolate_);
      v8::Isolate::Scope isolate_scope(isolate_);
      v8::HandleScope handle_scope(isolate_);
      v8::Local<v8::Context> context = v8::Context::New(isolate_);
      {
        v8::Context::Scope context_scope(context);
        CalcFibAndCheck(context);
      }
      {
        LockIsolateAndCalculateFibSharedContextThread thread(isolate_, context);
        isolate_->Exit();
        v8::Unlocker unlocker(isolate_);
        thread.Start();
        thread.Join();
      }
      isolate_->Enter();
      {
        v8::Context::Scope context_scope(context);
        CalcFibAndCheck(context);
      }
    }
    isolate_->DiscardThreadSpecificMetadata();
    isolate_->DiscardThreadSpecificMetadata();  // No-op
  }

 private:
  v8::Isolate* isolate_;
};


// Use unlocker inside of a Locker, multiple threads.
TEST(LockerUnlocker) {
  i::FLAG_always_opt = false;
#if V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  i::List<JoinableThread*> threads(kNThreads);
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  for (int i = 0; i < kNThreads; i++) {
    threads.Add(new LockerUnlockerThread(isolate));
  }
  StartJoinAndDeleteThreads(threads);
  isolate->Dispose();
}

class LockTwiceAndUnlockThread : public JoinableThread {
 public:
  explicit LockTwiceAndUnlockThread(v8::Isolate* isolate)
    : JoinableThread("LockTwiceAndUnlockThread"),
      isolate_(isolate) {
  }

  virtual void Run() {
    v8::Locker lock(isolate_);
    v8::Isolate::Scope isolate_scope(isolate_);
    v8::HandleScope handle_scope(isolate_);
    v8::Local<v8::Context> context = v8::Context::New(isolate_);
    {
      v8::Context::Scope context_scope(context);
      CalcFibAndCheck(context);
    }
    {
      v8::Locker second_lock(isolate_);
      {
        LockIsolateAndCalculateFibSharedContextThread thread(isolate_, context);
        isolate_->Exit();
        v8::Unlocker unlocker(isolate_);
        thread.Start();
        thread.Join();
      }
    }
    isolate_->Enter();
    {
      v8::Context::Scope context_scope(context);
      CalcFibAndCheck(context);
    }
  }

 private:
  v8::Isolate* isolate_;
};


// Use Unlocker inside two Lockers.
TEST(LockTwiceAndUnlock) {
  i::FLAG_always_opt = false;
#if V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  i::List<JoinableThread*> threads(kNThreads);
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  for (int i = 0; i < kNThreads; i++) {
    threads.Add(new LockTwiceAndUnlockThread(isolate));
  }
  StartJoinAndDeleteThreads(threads);
  isolate->Dispose();
}

class LockAndUnlockDifferentIsolatesThread : public JoinableThread {
 public:
  LockAndUnlockDifferentIsolatesThread(v8::Isolate* isolate1,
                                       v8::Isolate* isolate2)
    : JoinableThread("LockAndUnlockDifferentIsolatesThread"),
      isolate1_(isolate1),
      isolate2_(isolate2) {
  }

  virtual void Run() {
    v8::base::SmartPointer<LockIsolateAndCalculateFibSharedContextThread>
        thread;
    v8::Locker lock1(isolate1_);
    CHECK(v8::Locker::IsLocked(isolate1_));
    CHECK(!v8::Locker::IsLocked(isolate2_));
    {
      v8::Isolate::Scope isolate_scope(isolate1_);
      v8::HandleScope handle_scope(isolate1_);
      v8::Local<v8::Context> context1 = v8::Context::New(isolate1_);
      {
        v8::Context::Scope context_scope(context1);
        CalcFibAndCheck(context1);
      }
      thread.Reset(new LockIsolateAndCalculateFibSharedContextThread(
          isolate1_, context1));
    }
    v8::Locker lock2(isolate2_);
    CHECK(v8::Locker::IsLocked(isolate1_));
    CHECK(v8::Locker::IsLocked(isolate2_));
    {
      v8::Isolate::Scope isolate_scope(isolate2_);
      v8::HandleScope handle_scope(isolate2_);
      v8::Local<v8::Context> context2 = v8::Context::New(isolate2_);
      {
        v8::Context::Scope context_scope(context2);
        CalcFibAndCheck(context2);
      }
      v8::Unlocker unlock1(isolate1_);
      CHECK(!v8::Locker::IsLocked(isolate1_));
      CHECK(v8::Locker::IsLocked(isolate2_));
      v8::Context::Scope context_scope(context2);
      thread->Start();
      CalcFibAndCheck(context2);
      thread->Join();
    }
  }

 private:
  v8::Isolate* isolate1_;
  v8::Isolate* isolate2_;
};


// Lock two isolates and unlock one of them.
TEST(LockAndUnlockDifferentIsolates) {
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate1 = v8::Isolate::New(create_params);
  v8::Isolate* isolate2 = v8::Isolate::New(create_params);
  LockAndUnlockDifferentIsolatesThread thread(isolate1, isolate2);
  thread.Start();
  thread.Join();
  isolate2->Dispose();
  isolate1->Dispose();
}

class LockUnlockLockThread : public JoinableThread {
 public:
  LockUnlockLockThread(v8::Isolate* isolate, v8::Local<v8::Context> context)
      : JoinableThread("LockUnlockLockThread"),
        isolate_(isolate),
        context_(isolate, context) {}

  virtual void Run() {
    v8::Locker lock1(isolate_);
    CHECK(v8::Locker::IsLocked(isolate_));
    CHECK(!v8::Locker::IsLocked(CcTest::isolate()));
    {
      v8::Isolate::Scope isolate_scope(isolate_);
      v8::HandleScope handle_scope(isolate_);
      v8::Local<v8::Context> context =
          v8::Local<v8::Context>::New(isolate_, context_);
      v8::Context::Scope context_scope(context);
      CalcFibAndCheck(context);
    }
    {
      v8::Unlocker unlock1(isolate_);
      CHECK(!v8::Locker::IsLocked(isolate_));
      CHECK(!v8::Locker::IsLocked(CcTest::isolate()));
      {
        v8::Locker lock2(isolate_);
        v8::Isolate::Scope isolate_scope(isolate_);
        v8::HandleScope handle_scope(isolate_);
        CHECK(v8::Locker::IsLocked(isolate_));
        CHECK(!v8::Locker::IsLocked(CcTest::isolate()));
        v8::Local<v8::Context> context =
            v8::Local<v8::Context>::New(isolate_, context_);
        v8::Context::Scope context_scope(context);
        CalcFibAndCheck(context);
      }
    }
  }

 private:
  v8::Isolate* isolate_;
  v8::Persistent<v8::Context> context_;
};


// Locker inside an Unlocker inside a Locker.
TEST(LockUnlockLockMultithreaded) {
#if V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  v8::Isolate::CreateParams create_params;
  create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
  v8::Isolate* isolate = v8::Isolate::New(create_params);
  i::List<JoinableThread*> threads(kNThreads);
  {
    v8::Locker locker_(isolate);
    v8::Isolate::Scope isolate_scope(isolate);
    v8::HandleScope handle_scope(isolate);
    v8::Local<v8::Context> context = v8::Context::New(isolate);
    for (int i = 0; i < kNThreads; i++) {
      threads.Add(new LockUnlockLockThread(
          isolate, context));
    }
  }
  StartJoinAndDeleteThreads(threads);
  isolate->Dispose();
}

class LockUnlockLockDefaultIsolateThread : public JoinableThread {
 public:
  explicit LockUnlockLockDefaultIsolateThread(v8::Local<v8::Context> context)
      : JoinableThread("LockUnlockLockDefaultIsolateThread"),
        context_(CcTest::isolate(), context) {}

  virtual void Run() {
    v8::Locker lock1(CcTest::isolate());
    {
      v8::Isolate::Scope isolate_scope(CcTest::isolate());
      v8::HandleScope handle_scope(CcTest::isolate());
      v8::Local<v8::Context> context =
          v8::Local<v8::Context>::New(CcTest::isolate(), context_);
      v8::Context::Scope context_scope(context);
      CalcFibAndCheck(context);
    }
    {
      v8::Unlocker unlock1(CcTest::isolate());
      {
        v8::Locker lock2(CcTest::isolate());
        v8::Isolate::Scope isolate_scope(CcTest::isolate());
        v8::HandleScope handle_scope(CcTest::isolate());
        v8::Local<v8::Context> context =
            v8::Local<v8::Context>::New(CcTest::isolate(), context_);
        v8::Context::Scope context_scope(context);
        CalcFibAndCheck(context);
      }
    }
  }

 private:
  v8::Persistent<v8::Context> context_;
};


// Locker inside an Unlocker inside a Locker for default isolate.
TEST(LockUnlockLockDefaultIsolateMultithreaded) {
#if V8_TARGET_ARCH_MIPS
  const int kNThreads = 50;
#else
  const int kNThreads = 100;
#endif
  Local<v8::Context> context;
  i::List<JoinableThread*> threads(kNThreads);
  {
    v8::Locker locker_(CcTest::isolate());
    v8::Isolate::Scope isolate_scope(CcTest::isolate());
    v8::HandleScope handle_scope(CcTest::isolate());
    context = v8::Context::New(CcTest::isolate());
    for (int i = 0; i < kNThreads; i++) {
      threads.Add(new LockUnlockLockDefaultIsolateThread(context));
    }
  }
  StartJoinAndDeleteThreads(threads);
}


TEST(Regress1433) {
  for (int i = 0; i < 10; i++) {
    v8::Isolate::CreateParams create_params;
    create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
    v8::Isolate* isolate = v8::Isolate::New(create_params);
    {
      v8::Locker lock(isolate);
      v8::Isolate::Scope isolate_scope(isolate);
      v8::HandleScope handle_scope(isolate);
      v8::Local<Context> context = v8::Context::New(isolate);
      v8::Context::Scope context_scope(context);
      v8::Local<String> source = v8_str("1+1");
      v8::Local<Script> script =
          v8::Script::Compile(context, source).ToLocalChecked();
      v8::Local<Value> result = script->Run(context).ToLocalChecked();
      v8::String::Utf8Value utf8(result);
    }
    isolate->Dispose();
  }
}


static const char* kSimpleExtensionSource =
  "(function Foo() {"
  "  return 4;"
  "})() ";

class IsolateGenesisThread : public JoinableThread {
 public:
  IsolateGenesisThread(int count, const char* extension_names[])
    : JoinableThread("IsolateGenesisThread"),
      count_(count),
      extension_names_(extension_names)
  {}

  virtual void Run() {
    v8::Isolate::CreateParams create_params;
    create_params.array_buffer_allocator = CcTest::array_buffer_allocator();
    v8::Isolate* isolate = v8::Isolate::New(create_params);
    {
      v8::Isolate::Scope isolate_scope(isolate);
      CHECK(
          !reinterpret_cast<i::Isolate*>(isolate)->has_installed_extensions());
      v8::ExtensionConfiguration extensions(count_, extension_names_);
      v8::HandleScope handle_scope(isolate);
      v8::Context::New(isolate, &extensions);
      CHECK(reinterpret_cast<i::Isolate*>(isolate)->has_installed_extensions());
    }
    isolate->Dispose();
  }

 private:
  int count_;
  const char** extension_names_;
};


// Test installing extensions in separate isolates concurrently.
// http://code.google.com/p/v8/issues/detail?id=1821
TEST(ExtensionsRegistration) {
#if V8_TARGET_ARCH_ARM || V8_TARGET_ARCH_MIPS
  const int kNThreads = 10;
#elif V8_TARGET_ARCH_X64 && V8_TARGET_ARCH_32_BIT
  const int kNThreads = 4;
#else
  const int kNThreads = 40;
#endif
  v8::RegisterExtension(new v8::Extension("test0",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test1",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test2",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test3",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test4",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test5",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test6",
                                          kSimpleExtensionSource));
  v8::RegisterExtension(new v8::Extension("test7",
                                          kSimpleExtensionSource));
  const char* extension_names[] = { "test0", "test1",
                                    "test2", "test3", "test4",
                                    "test5", "test6", "test7" };
  i::List<JoinableThread*> threads(kNThreads);
  for (int i = 0; i < kNThreads; i++) {
    threads.Add(new IsolateGenesisThread(8, extension_names));
  }
  StartJoinAndDeleteThreads(threads);
}