Merge branch 'dygraph' into fix_doc

deploy/cpp_infer/src/main.cpp

@@ -50,6 +50,11 @@ int main(int argc, char **argv) {
 
   cv::Mat srcimg = cv::imread(img_path, cv::IMREAD_COLOR);
 
+  if (!srcimg.data) {
+    std::cerr << "[ERROR] image read failed! image path: " << img_path << "\n";
+    exit(1);
+  }
+
   DBDetector det(config.det_model_dir, config.use_gpu, config.gpu_id,
                  config.gpu_mem, config.cpu_math_library_num_threads,
                  config.use_mkldnn, config.max_side_len, config.det_db_thresh,

tools/train.py

@@ -89,8 +89,10 @@ def main(config, device, logger, vdl_writer):
     # load pretrain model
     pre_best_model_dict = init_model(config, model, logger, optimizer)
 
-    logger.info('train dataloader has {} iters, valid dataloader has {} iters'.
-                format(len(train_dataloader), len(valid_dataloader)))
+    logger.info('train dataloader has {} iters'.format(len(train_dataloader)))
+    if valid_dataloader is not None:
+        logger.info('valid dataloader has {} iters'.format(
+            len(valid_dataloader)))
     # start train
     program.train(config, train_dataloader, valid_dataloader, device, model,
                   loss_class, optimizer, lr_scheduler, post_process_class,