Add --print-benchmarking-metrics to the VM for Golem.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 7708047f003a3f7acb3a28d864f45718a26aeba5..fd4a3835c6753f4342ef691c8b3b67b0e832203f 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -1177,6 +1177,20 @@ bool Isolate::MakeRunnable() {
       event->Complete();
     }
   }
+  if (FLAG_print_benchmarking_metrics) {
+    // is_service_isolate not set yet.
+    if (!ServiceIsolate::NameEquals(name())) {

[Florian Schneider, 2016/12/14 18:22:47]

Maybe only print the metrics for the main isolate?

+      int64_t uptime = OS::GetCurrentTimeMicros() - start_time();
+      OS::Print("MakeRunnable(Latency): %" Pd64 " us.\n", uptime);
+      {
+        StartIsolateScope scope(this);
+        heap()->CollectAllGarbage();
+      }
+      int64_t heap_size = (heap()->UsedInWords(Heap::kNew) * kWordSize) +
+                          (heap()->UsedInWords(Heap::kOld) * kWordSize);
+      OS::Print("MakeRunnable(HeapSize): %" Pd64 " B.\n", heap_size);
+    }
+  }
   if (FLAG_support_service && Service::isolate_stream.enabled()) {
     ServiceEvent runnableEvent(this, ServiceEvent::kIsolateRunnable);
     Service::HandleEvent(&runnableEvent);