[Model][Tutorial] Fix capsule memory leak (#185)

* fix memory leak & Remove unnecessary initializer

* change confused name

* fix name

* Move func outside loop

* fix name inconsistency

examples/pytorch/capsule/DGLDigitCapsule.py

@@ -22,7 +22,6 @@ class DGLDigitCapsuleLayer(nn.Module):
                                   device=self.device)
         routing(u_hat, routing_num=3)
         out_nodes_feature = routing.g.nodes[routing.out_indx].data['v']
-        routing.end()
         # shape transformation is for further classification
         return out_nodes_feature.transpose(0, 1).unsqueeze(1).unsqueeze(4).squeeze(1)
 

examples/pytorch/capsule/DGLRoutingLayer.py

@@ -8,7 +8,7 @@ class DGLRoutingLayer(nn.Module):
     def __init__(self, in_nodes, out_nodes, f_size, batch_size=0, device='cpu'):
         super(DGLRoutingLayer, self).__init__()
         self.batch_size = batch_size
-        self.g = init_graph(in_nodes, out_nodes, f_size, device=device, batch_size=batch_size)
+        self.g = init_graph(in_nodes, out_nodes, f_size, device=device)
         self.in_nodes = in_nodes
         self.out_nodes = out_nodes
         self.in_indx = list(range(in_nodes))
@@ -17,22 +17,26 @@ class DGLRoutingLayer(nn.Module):
 
     def forward(self, u_hat, routing_num=1):
         self.g.edata['u_hat'] = u_hat
-        for r in range(routing_num):
-            # step 1 (line 4): normalize over out edges
-            in_edges = self.g.edata['b'].view(self.in_nodes, self.out_nodes)
-            self.g.edata['c'] = F.softmax(in_edges, dim=1).view(-1, 1)
+        batch_size = self.batch_size
+
+        # step 2 (line 5)
+        def cap_message(edges):
+            if batch_size:
+                return {'m': edges.data['c'].unsqueeze(1) * edges.data['u_hat']}
+            else:
+                return {'m': edges.data['c'] * edges.data['u_hat']}
+
+        self.g.register_message_func(cap_message)
 
-            def cap_message(edges):
-                if self.batch_size:
-                    return {'m': edges.data['c'].unsqueeze(1) * edges.data['u_hat']}
-                else:
-                    return {'m': edges.data['c'] * edges.data['u_hat']}
-            self.g.register_message_func(cap_message)
+        def cap_reduce(nodes):
+            return {'s': th.sum(nodes.mailbox['m'], dim=1)}
 
-            # step 2 (line 5)
-            def cap_reduce(nodes):
-                return {'s': th.sum(nodes.mailbox['m'], dim=1)}
-            self.g.register_reduce_func(cap_reduce)
+        self.g.register_reduce_func(cap_reduce)
+
+        for r in range(routing_num):
+            # step 1 (line 4): normalize over out edges
+            edges_b = self.g.edata['b'].view(self.in_nodes, self.out_nodes)
+            self.g.edata['c'] = F.softmax(edges_b, dim=1).view(-1, 1)
 
             # Execute step 1 & 2
             self.g.update_all()
@@ -50,13 +54,6 @@ class DGLRoutingLayer(nn.Module):
             else:
                 self.g.edata['b'] = self.g.edata['b'] + (self.g.edata['u_hat'] * v).sum(dim=1, keepdim=True)
 
-    def end(self):
-        del self.g
-        # del self.g.edata['u_hat']
-        # del self.g.ndata['v']
-        # del self.g.ndata['s']
-        # del self.g.edata['b']
-
 
 def squash(s, dim=1):
     sq = th.sum(s ** 2, dim=dim, keepdim=True)
@@ -65,8 +62,9 @@ def squash(s, dim=1):
     return s
 
 
-def init_graph(in_nodes, out_nodes, f_size, device='cpu', batch_size=0):
+def init_graph(in_nodes, out_nodes, f_size, device='cpu'):
     g = dgl.DGLGraph()
+    g.set_n_initializer(dgl.frame.zero_initializer)
     all_nodes = in_nodes + out_nodes
     g.add_nodes(all_nodes)
     in_indx = list(range(in_nodes))
@@ -75,10 +73,5 @@ def init_graph(in_nodes, out_nodes, f_size, device='cpu', batch_size=0):
     for u in in_indx:
         g.add_edges(u, out_indx)
 
-    # init states
-    if batch_size:
-        g.ndata['v'] = th.zeros(all_nodes, batch_size, f_size).to(device)
-    else:
-        g.ndata['v'] = th.zeros(all_nodes, f_size).to(device)
     g.edata['b'] = th.zeros(in_nodes * out_nodes, 1).to(device)
     return g