From 1f26c65254268730b7409f517d1ed1b554d01e50 Mon Sep 17 00:00:00 2001
From: Shanqing Cai <cais@google.com>
Date: Mon, 29 Jan 2018 10:22:10 -0800
Subject: [PATCH] tfdbg: let session wrappers handle empty fetches correctly

Fixes: #15882
PiperOrigin-RevId: 183685645
---
 .../python/debug/wrappers/dumping_wrapper_test.py  |  5 +++++
 tensorflow/python/debug/wrappers/framework.py      |  9 ++++++++-
 .../debug/wrappers/local_cli_wrapper_test.py       | 14 ++++++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/tensorflow/python/debug/wrappers/dumping_wrapper_test.py b/tensorflow/python/debug/wrappers/dumping_wrapper_test.py
index acea9433e22..254201c3937 100644
--- a/tensorflow/python/debug/wrappers/dumping_wrapper_test.py
+++ b/tensorflow/python/debug/wrappers/dumping_wrapper_test.py
@@ -389,6 +389,11 @@ class DumpingDebugWrapperSessionTest(test_util.TensorFlowTestCase):
         r"mode\."):
       sess.invoke_node_stepper(node_stepper)
 
+  def testDumpingWrapperWithEmptyFetchWorks(self):
+    sess = dumping_wrapper.DumpingDebugWrapperSession(
+        self.sess, session_root=self.session_root, log_usage=False)
+    sess.run([])
+
 
 if __name__ == "__main__":
   googletest.main()
diff --git a/tensorflow/python/debug/wrappers/framework.py b/tensorflow/python/debug/wrappers/framework.py
index 909150eb6aa..c530204bbf6 100644
--- a/tensorflow/python/debug/wrappers/framework.py
+++ b/tensorflow/python/debug/wrappers/framework.py
@@ -121,7 +121,9 @@ from tensorflow.python.debug.lib import debug_utils
 from tensorflow.python.debug.lib import stepper
 from tensorflow.python.framework import errors
 from tensorflow.python.framework import ops
+from tensorflow.python.platform import tf_logging
 from tensorflow.python.training import monitored_session
+from tensorflow.python.util import nest
 
 
 # Helper function.
@@ -439,7 +441,12 @@ class BaseDebugWrapperSession(session.SessionInterface):
             "callable_runner and fetches/feed_dict are mutually exclusive, but "
             "are used simultaneously.")
 
-    if self._is_disabled_thread():
+    empty_fetches = not nest.flatten(fetches)
+    if empty_fetches:
+      tf_logging.info(
+          "Due to empty fetches, tfdbg Session wrapper is letting a "
+          "Session.run pass through without any debugging actions.")
+    if self._is_disabled_thread() or empty_fetches:
       if callable_runner:
         return callable_runner(*callable_runner_args)
       else:
diff --git a/tensorflow/python/debug/wrappers/local_cli_wrapper_test.py b/tensorflow/python/debug/wrappers/local_cli_wrapper_test.py
index 770a496aa9d..490812c96d8 100644
--- a/tensorflow/python/debug/wrappers/local_cli_wrapper_test.py
+++ b/tensorflow/python/debug/wrappers/local_cli_wrapper_test.py
@@ -664,6 +664,20 @@ class LocalCLIDebugWrapperSessionTest(test_util.TensorFlowTestCase):
         [["run"], ["run"]], monitored_sess)
     self.assertFalse(wrapped_monitored_sess.should_stop())
 
+  def testRunsWithEmptyFetchWorks(self):
+    wrapped_sess = LocalCLIDebuggerWrapperSessionForTest(
+        [["run"]], self.sess, dump_root="")
+
+    run_output = wrapped_sess.run([])
+    self.assertEqual([], run_output)
+
+  def testRunsWithEmptyNestedFetchWorks(self):
+    wrapped_sess = LocalCLIDebuggerWrapperSessionForTest(
+        [["run"]], self.sess, dump_root="")
+
+    run_output = wrapped_sess.run({"foo": {"baz": []}, "bar": ()})
+    self.assertEqual({"foo": {"baz": []}, "bar": ()}, run_output)
+
 
 if __name__ == "__main__":
   googletest.main()