Added isolate + thread high watermark tracking to Observatory

runtime/vm/thread_registry.cc

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/thread_registry.h"
 
 #include "vm/isolate.h"
 #include "vm/json_stream.h"
 #include "vm/lockers.h"
 
@@ skipping 152 matching lines @@
   // Get thread structure from free list or create a new one.
   if (free_list_ == NULL) {
     thread = new Thread(isolate);
   } else {
     thread = free_list_;
     free_list_ = thread->next_;
   }
   return thread;
 }
 
+
 void ThreadRegistry::ReturnToFreelistLocked(Thread* thread) {
   ASSERT(thread != NULL);
   ASSERT(thread->os_thread_ == NULL);
   ASSERT(thread->isolate_ == NULL);
   ASSERT(thread->heap_ == NULL);
   ASSERT(threads_lock()->IsOwnedByCurrentThread());
   // Add thread to the free list.
   thread->next_ = free_list_;
   free_list_ = thread;
 }
 
+
+uint ThreadRegistry::ThreadHighWatermarksTotalLocked() const {
+  ASSERT(threads_lock()->IsOwnedByCurrentThread());
+  uint memory_high_watermarks_total = 0;
+  Thread* current = active_list_;
+  while (current != NULL) {
+    memory_high_watermarks_total += current->memory_high_watermark();
+    current = current->next_;
+  }
+  return memory_high_watermarks_total;

[siva, 2017/01/21 00:30:51]

Why is it necessary to sum up the high water marks of the threads here and add
it up in this fashion. This code is racy and triggers an error from a tsan run.


Is tracking the high water mark for the isolate critical, could we
not just display the high water mark of each thread?

+}
+
 }  // namespace dart