Rename release_all -> empty_cache and provide documentation

python/mxnet/context.py

@@ -145,7 +145,20 @@ def default_ctx(cls, val):
         cls._default_ctx.value = val
     #pylint: enable=no-self-argument
 
-    def release_all(self):
+    def empty_cache(self):
+        """Empties the memory cache for the current contexts device.
+
+		MXNet utilizes a memory pool to avoid excessive allocations. 
+		Calling empty_cache will empty the memory pool of the contexts
+		device. This will only free the memory of unreferenced data.
+
+        Examples
+        -------
+		>>> ctx = mx.gpu(0)
+        >>> arr = mx.nd.ones((200,200), ctx=ctx)
+        >>> del arr
+        >>> ctx.empty_cache() # forces release of memory allocated for arr
+        """
         dev_type = ctypes.c_int(self.device_typeid)
         dev_id = ctypes.c_int(self.device_id)
         check_call(_LIB.MXStorageReleaseAll(dev_type, dev_id))