Fix the problem that no enough placeholders for persistent tensor

batch delete

The deleter_key is always a device_name, hence there is only one
of it. Hence, we cannot delete >1 handles at one time.

In the fix, it creates delete placeholder on demand, the max
number of placeholders is _DEAD_HANDLES_THRESHOLD.
Change: 152322770

2 files changed, 6 insertions, 11 deletions

diff --git a/tensorflow/python/client/session.py b/tensorflow/python/client/session.py
index 6900ac9a4f..5b50df3ed3 100644
--- a/tensorflow/python/client/session.py
+++ b/tensorflow/python/client/session.py
@@ -1094,8 +1094,9 @@ class BaseSession(SessionInterface):
     if tensors_to_delete:
       feeds = {}
       fetches = []
-      for tensor_handle in tensors_to_delete:
+      for deleter_key, tensor_handle in enumerate(tensors_to_delete):
         holder, deleter = session_ops._get_handle_deleter(self.graph,
+                                                          deleter_key,
                                                           tensor_handle)
         feeds[holder] = tensor_handle
         fetches.append(deleter)
diff --git a/tensorflow/python/ops/session_ops.py b/tensorflow/python/ops/session_ops.py
index 0a06982ad7..3d038cfd8a 100644
--- a/tensorflow/python/ops/session_ops.py
+++ b/tensorflow/python/ops/session_ops.py
@@ -116,7 +116,7 @@ class TensorHandle(object):
       raise TypeError("Persistent tensor %s may have already been deleted."
                       % self.handle)
     self._auto_gc_enabled = False
-    holder, deleter = _get_handle_deleter(self._session.graph, self._handle)
+    holder, deleter = _get_handle_deleter(self._session.graph, 0, self._handle)
     self._session.run(deleter, feed_dict={holder: self.handle})
 
   def get_raw_handle(self):
@@ -142,11 +142,6 @@ class TensorHandle(object):
     return handle_parts[0] + ";" + handle_parts[-1]
 
   @staticmethod
-  def _get_deleter_key(handle):
-    """The graph key for deleter."""
-    return str(handle).split(";")[-1]
-
-  @staticmethod
   def _get_mover_key(feeder, handle):
     """The graph key for mover."""
     return feeder.op.name + ";" + TensorHandle._get_reader_key(handle)
@@ -302,10 +297,9 @@ def _get_handle_mover(graph, feeder, handle):
   return result
 
 
-def _get_handle_deleter(graph, handle):
+def _get_handle_deleter(graph, deleter_key, handle):
   """Return a deletion subgraph for this handle."""
-  graph_key = TensorHandle._get_deleter_key(handle)
-  result = graph._handle_deleters.get(graph_key)
+  result = graph._handle_deleters.get(deleter_key)
   if result is None:
     # Create deleter if we haven't done it.
     handle_device = TensorHandle._get_device_name(handle)
@@ -313,5 +307,5 @@ def _get_handle_deleter(graph, handle):
       holder = array_ops.placeholder(dtypes.string)
       deleter = gen_data_flow_ops._delete_session_tensor(holder)
     result = (holder, deleter)
-    graph._handle_deleters[graph_key] = result
+    graph._handle_deleters[deleter_key] = result
   return result