Updated MallocHooks to collect stack traces when memory is allocated.

runtime/vm/dart.cc

Index: runtime/vm/dart.cc
diff --git a/runtime/vm/dart.cc b/runtime/vm/dart.cc
index 916e81bb14824779a26edcc42172197091448e00..94111a5f9ff67658b3511f0dd6ef67f3ab490f2c 100644
--- a/runtime/vm/dart.cc
+++ b/runtime/vm/dart.cc
@@ -152,7 +152,6 @@ char* Dart::InitOnce(const uint8_t* vm_isolate_snapshot,
   start_time_micros_ = OS::GetCurrentMonotonicMicros();
   VirtualMemory::InitOnce();
   OSThread::InitOnce();
-  MallocHooks::InitOnce();
   if (FLAG_support_timeline) {
     Timeline::InitOnce();
   }
@@ -233,6 +232,8 @@ char* Dart::InitOnce(const uint8_t* vm_isolate_snapshot,
         return strdup("Precompiled runtime requires a precompiled snapshot");
 #else
         StubCode::InitOnce();
+        // MallocHooks can't be initialized until StubCode has been.

[Cutch, 2017/02/15 08:21:00]

maybe add why?

[bkonyi, 2017/02/16 00:28:28]

Done.

+        MallocHooks::InitOnce();
 #endif
       } else {
         return strdup("Invalid vm isolate snapshot seen");
@@ -271,6 +272,8 @@ char* Dart::InitOnce(const uint8_t* vm_isolate_snapshot,
 #else
       vm_snapshot_kind_ = Snapshot::kNone;
       StubCode::InitOnce();
+      // Malloc hooks can't be initialized until StubCode has been.
+      MallocHooks::InitOnce();

[zra, 2017/02/15 05:50:45]

Maybe add a TODO to separate initialization of the hooks from the beginning of
collecting stack traces. That way we can at least have a (more) accurate count
of the malloc'd memory.

[bkonyi, 2017/02/16 00:28:28]

Done.

       Symbols::InitOnce(vm_isolate_);
 #endif
     }