Introduce --job-based-sweeping flag and use individual jobs for sweeping if set

src/sweeper-thread.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // 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
@@ skipping 27 matching lines @@
 static const int kSweeperThreadStackSize = 64 * KB;
 
 SweeperThread::SweeperThread(Isolate* isolate)
      : Thread(Thread::Options("v8:SweeperThread", kSweeperThreadStackSize)),
        isolate_(isolate),
        heap_(isolate->heap()),
        collector_(heap_->mark_compact_collector()),
        start_sweeping_semaphore_(0),
        end_sweeping_semaphore_(0),
        stop_semaphore_(0) {
+  ASSERT(!FLAG_job_based_sweeping);
   NoBarrier_Store(&stop_thread_, static_cast<AtomicWord>(false));
 }
 
 
 void SweeperThread::Run() {
   Isolate::SetIsolateThreadLocals(isolate_, NULL);
   DisallowHeapAllocation no_allocation;
   DisallowHandleAllocation no_handles;
   DisallowHandleDereference no_deref;
 
@@ skipping 32 matching lines @@
 
 int SweeperThread::NumberOfThreads(int max_available) {
   if (!FLAG_concurrent_sweeping && !FLAG_parallel_sweeping) return 0;
   if (FLAG_sweeper_threads > 0) return FLAG_sweeper_threads;
   if (FLAG_concurrent_sweeping) return max_available - 1;
   ASSERT(FLAG_parallel_sweeping);
   return max_available;
 }
 
 } }  // namespace v8::internal