--- a/mercurial/dirstate.py	Thu Oct 26 16:15:31 2017 -0700
+++ b/mercurial/dirstate.py	Thu Oct 26 16:15:36 2017 -0700
@@ -129,7 +129,7 @@
     def _map(self):
         '''Return the dirstate contents as a map from filename to
         (state, mode, size, time).'''
-        self._read()
+        self._map = dirstatemap(self._ui, self._opener, self._root)
         return self._map
 
     @property
@@ -353,10 +353,6 @@
             f.discard()
             raise
 
-    def _read(self):
-        self._map = dirstatemap(self._ui, self._opener, self._root)
-        self._map.read()
-
     def invalidate(self):
         '''Causes the next access to reread the dirstate.
 
@@ -1201,14 +1197,24 @@
         self._root = root
         self._filename = 'dirstate'
 
-        self._map = {}
-        self.copymap = {}
         self._parents = None
         self._dirtyparents = False
 
         # for consistent view between _pl() and _read() invocations
         self._pendingmode = None
 
+    @propertycache
+    def _map(self):
+        self._map = {}
+        self.read()
+        return self._map
+
+    @propertycache
+    def copymap(self):
+        self.copymap = {}
+        self._map
+        return self.copymap
+
     def clear(self):
         self._map = {}
         self.copymap = {}
@@ -1388,7 +1394,7 @@
 
     @propertycache
     def identity(self):
-        self.read()
+        self._map
         return self.identity
 
     @propertycache