1.im2rec.py调试错误：multiprocessing not available, fall back to single threaded encoding imread
经过查找发现是程序中args.num_thread默认的个数是1，改为大于1的数即可
2.：mxnet.base.MXNetError: [17:31:26] src/io/input_split_base.cc:173: Check failed: files_.size() != 0U (0 vs. 0) Cannot find any files that matches the URI pattern ./data/train_depth_all_112_58532.rec
谷歌后发现是.rec文件中为空，导致找不到
https://discuss.gluon.ai/t/topic/3331/42