Copy the thread name to the stack for debugging purposes.

base/threading/thread.cc

 // Copyright (c) 2012 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/threading/thread.h"
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
 #include "base/threading/thread_id_name_manager.h"
@@ skipping 154 matching lines @@
 bool Thread::GetThreadWasQuitProperly() {
   bool quit_properly = true;
 #ifndef NDEBUG
   quit_properly = lazy_tls_bool.Pointer()->Get();
 #endif
   return quit_properly;
 }
 
 void Thread::ThreadMain() {
   {
+#if defined(OS_MACOSX)
+    // Store the thread name on the stack to debug <http://crbug.com/274705>.
+    // End with a byte sequence of <EOT><BEL><NUL> to make it easier to grep in
+    // the minidump stack dump.

[Mark Mentovai, 2013/09/12 18:38:37]

If you’re trying to make it easier to find in a minidump, you probably also want
to zero out unused bytes so that they don’t look like garbage.

[Robert Sesek, 2013/09/12 18:47:53]

If strlen(s2) < n, then it fills the remainder with \0. But I {0} it for you.

+    const size_t kThreadNameSize = 50;
+    char thread_name[kThreadNameSize];
+    strncpy(thread_name, name_.c_str(), kThreadNameSize);
+    thread_name[kThreadNameSize - 1] = '\0';
+    thread_name[kThreadNameSize - 2] = '\7';
+    thread_name[kThreadNameSize - 3] = '\3';

[Mark Mentovai, 2013/09/12 18:38:37]

How are you assuring that storage for variable, unused after this point, won’t
be recycled for other purposes by an optimizing compiler? For that matter, the
compiler may have sufficient intelligence to reason that this code is all
side-effect-free and completely optimize it out entirely.

[Robert Sesek, 2013/09/12 18:47:53]

Good point. Using base::debug::Alias() now at the top and bottom of this scope.

+#endif
+
     // The message loop for this thread.
     // Allocated on the heap to centralize any leak reports at this line.
     scoped_ptr<MessageLoop> message_loop(
         new MessageLoop(startup_data_->options.message_loop_type));
 
     // Complete the initialization of our Thread object.
     thread_id_ = PlatformThread::CurrentId();
     PlatformThread::SetName(name_.c_str());
     ANNOTATE_THREAD_NAME(name_.c_str());  // Tell the name to race detector.
     message_loop->set_thread_name(name_);
@@ skipping 29 matching lines @@
 
     // Assert that MessageLoop::Quit was called by ThreadQuitHelper.
     DCHECK(GetThreadWasQuitProperly());
 
     // We can't receive messages anymore.
     message_loop_ = NULL;
   }
 }
 
 }  // namespace base