Add --print_stacktrace_at_api_error.

runtime/vm/thread_pool.cc

 // Copyright (c) 2012, 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_pool.h"
 
 #include "vm/dart.h"
 #include "vm/flags.h"
 #include "vm/lockers.h"
 
@@ skipping 429 matching lines @@
 
 // static
 void ThreadPool::Worker::Main(uword args) {
   Worker* worker = reinterpret_cast<Worker*>(args);
   OSThread* os_thread = OSThread::Current();
   ASSERT(os_thread != NULL);
   ThreadId id = os_thread->id();
   ThreadPool* pool;
 
   // Set the thread's stack_base based on the current stack pointer.
-  os_thread->set_stack_base(Thread::GetCurrentStackPointer());
+  uword current_sp = Thread::GetCurrentStackPointer();
+  if (current_sp > os_thread->stack_base()) {
+    os_thread->set_stack_base(current_sp);
+  }

[siva, 2017/04/13 01:50:18]

Which situation causes the code inside the 'if' statement to be executed?

 
   {
     MonitorLocker ml(&worker->monitor_);
     ASSERT(worker->task_);
     worker->id_ = id;
     pool = worker->pool_;
   }
 
   bool released = worker->Loop();
 
@@ skipping 39 matching lines @@
   }
 
   // Call the thread exit hook here to notify the embedder that the
   // thread pool thread is exiting.
   if (Dart::thread_exit_callback() != NULL) {
     (*Dart::thread_exit_callback())();
   }
 }
 
 }  // namespace dart