log for logical blob with bw op consumers

Former-commit-id: f015a245efa5e0791bb1e5070b217e3fec616fc9

oneflow/core/job_rewriter/checkpointing_pass.cpp

@@ -120,6 +120,31 @@ void GenConnectedCheckpointingSubgraphs(
 }
 
 Maybe<void> CheckpointingPass::Apply(const OpGraph& op_graph, JobBuilder* job_builder) const {
+  op_graph.TopoForEachNode([&](const OpNode* op_node) {
+    HashMap<std::string, HashSet<std::string>> lbn2bw_consumer_op_names;
+    for (const OpEdge* out_edge : op_node->out_edges()) {
+      bool is_bw_consumer = false;
+      const OpNode* out_node = out_edge->dst_node();
+      if (!IsForwardPassScope(Scope4OpNode(out_node))) { is_bw_consumer = true; }
+      for (const auto& lbi : out_edge->lbis()) {
+        std::string lbn = GenLogicalBlobName(lbi);
+        auto& bw_consumer_op_names = lbn2bw_consumer_op_names[lbn];
+        if (is_bw_consumer) { bw_consumer_op_names.insert(out_node->op().op_name()); }
+      }
+    }
+    for (const auto& pair : lbn2bw_consumer_op_names) {
+      int op_num = pair.second.size();
+      LOG(INFO) << "Checkpointing log: lbn = " << pair.first
+                << ", bw_consumer_op_num =  " << op_num;
+      if (op_num > 0) {
+        std::string log_str = "They are: {";
+        for (const auto& bw_op_name : pair.second) { log_str += bw_op_name + ","; }
+        log_str += "}";
+        LOG(INFO) << log_str;
+      }
+    }
+  });
+
   // step 1. collect all checkpointing ops in forwardpass.
   HashMap<std::string, const OpNode*> checkpointing_op_name2op_node;
   CollectAllCheckpointingOpsInForwardPass(op_graph, &checkpointing_op_name2op_node);