Track thread activities in order to diagnose hangs.

base/debug/task_annotator.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/debug/task_annotator.h"
 
+#include "base/debug/activity_tracker.h"
 #include "base/debug/alias.h"
 #include "base/pending_task.h"
 #include "base/trace_event/trace_event.h"
 #include "base/tracked_objects.h"
 
 namespace base {
 namespace debug {
 
 TaskAnnotator::TaskAnnotator() {
 }
 
 TaskAnnotator::~TaskAnnotator() {
 }
 
 void TaskAnnotator::DidQueueTask(const char* queue_function,
                                  const PendingTask& pending_task) {
   TRACE_EVENT_WITH_FLOW0(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
                           queue_function,
                           TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
                           TRACE_EVENT_FLAG_FLOW_OUT);
 }
 
 void TaskAnnotator::RunTask(const char* queue_function,
                             const PendingTask& pending_task) {
+  ScopedTaskActivity activity(pending_task);
+
   tracked_objects::TaskStopwatch stopwatch;
   stopwatch.Start();
   tracked_objects::Duration queue_duration =
       stopwatch.StartTime() - pending_task.EffectiveTimePosted();
 
   TRACE_EVENT_WITH_FLOW1(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
                           queue_function,
                           TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
                           TRACE_EVENT_FLAG_FLOW_IN,
                           "queue_duration",
                           queue_duration.InMilliseconds());
 
   // Before running the task, store the program counter where it was posted
   // and deliberately alias it to ensure it is on the stack if the task
   // crashes. Be careful not to assume that the variable itself will have the
   // expected value when displayed by the optimizer in an optimized build.
   // Look at a memory dump of the stack.
   const void* program_counter = pending_task.posted_from.program_counter();

[Sigurður Ásgeirsson, 2016/05/20 13:16:53]

can we subsume some or all of the stuff here - queueing time is quite
interesting post-mortem, as a case in point?

[bcwhite, 2016/05/20 19:19:19]

Dunno.  Something to consider once we know what it isn't providing.

   debug::Alias(&program_counter);
 
   pending_task.task.Run();
 
   stopwatch.Stop();
   tracked_objects::ThreadData::TallyRunOnNamedThreadIfTracking(
       pending_task, stopwatch);
 }
 
 uint64_t TaskAnnotator::GetTaskTraceID(const PendingTask& task) const {
   return (static_cast<uint64_t>(task.sequence_num) << 32) |
          ((static_cast<uint64_t>(reinterpret_cast<intptr_t>(this)) << 32) >>
           32);
 }
 
 }  // namespace debug
 }  // namespace base