fix size count in LMDBData

.travis.yml

@@ -58,7 +58,7 @@ notifications:
     recipients:
       - ppwwyyxxc@gmail.com
     on_success: never
-    on_failure: change
+    on_failure: always
 - webhooks:
     urls:
       - https://webhooks.gitter.im/e/cede9dbbf6630b3704b3

tensorpack/dataflow/format.py

@@ -79,8 +79,9 @@ class LMDBData(RNGDataFlow):
         self._shuffle = shuffle
 
         self.open_lmdb()
-        logger.info("Found {} entries in {}".format(self._size, self._lmdb_path))
+        self._size = self._txn.stat()['entries']
         self._set_keys(keys)
+        logger.info("Found {} entries in {}".format(self._size, self._lmdb_path))
 
     def _set_keys(self, keys=None):
         def find_keys(txn, size):
@@ -94,12 +95,16 @@ class LMDBData(RNGDataFlow):
                     pbar.update()
             return keys
 
-        if self._shuffle:
-            if keys is None:
-                # get the list of keys either from __keys__ or by iterating
         try:
             self.keys = loads(self._txn.get('__keys__'))
-                except Exception:
+        except:
+            self.keys = None
+        else:
+            self._size -= 1     # delete this item
+
+        if self._shuffle:
+            if keys is None:
+                if self.keys is None:
                     self.keys = find_keys(self._txn, self._size)
             else:
                 # check if key-format like '{:0>8d}' was given
@@ -114,7 +119,6 @@ class LMDBData(RNGDataFlow):
                                readonly=True, lock=False, readahead=True,
                                map_size=1099511627776 * 2, max_readers=100)
         self._txn = self._lmdb.begin()
-        self._size = self._txn.stat()['entries']
 
     def reset_state(self):
         self._lmdb.close()