Ignore get_configs that aren't JSON-serializable when saving checkpoints

This is extra "nice to have" metadata, and otherwise it looks like a checkpointing error. Not worth bothering people about.

PiperOrigin-RevId: 235247436

tensorflow/python/training/tracking/base.py

@@ -851,10 +851,14 @@ class Trackable(object):
       """Serializes `self.get_config()` for saving."""
       dereferenced_self = weak_self()
       if dereferenced_self:
+        try:
           return json.dumps(
               dereferenced_self,
               default=serialization.get_json_type,
               sort_keys=True).encode("utf8")
+        except TypeError:
+          # Even if get_config worked objects may have produced garbage.
+          return ""
       else:
         return ""
     return {OBJECT_CONFIG_JSON_KEY: functools.partial(

tensorflow/python/training/tracking/base_test.py

@@ -83,6 +83,19 @@ class InterfaceTests(test.TestCase):
     with self.assertRaisesRegexp(AssertionError, "foo_attr"):
       status.assert_consumed()
 
+  def testBuggyGetConfig(self):
+
+    class NotSerializable(object):
+      pass
+
+    class GetConfigRaisesError(base.Trackable):
+
+      def get_config(self):
+        return NotSerializable()
+
+    util.Checkpoint(obj=GetConfigRaisesError()).save(
+        os.path.join(self.get_temp_dir(), "ckpt"))
+
 
 if __name__ == "__main__":
   ops.enable_eager_execution()