Unknown: RuntimeError: This DataFlow is not reentrant

[rlrahulkanojia]

This occurs during training after each epoch.

Epoch 4 Step 5280/5304 : Loss paf 20.2253532 Loss heatmap 57.0472374 Total loss 158.943283
Epoch 4 Step 5290/5304 : Loss paf 35.3798218 Loss heatmap 69.6211166 Total loss 213.979401
Epoch 4 Step 5300/5304 : Loss paf 25.4680023 Loss heatmap 53.8446045 Total loss 162.881088
2020-04-01 13:25:00.352075: W tensorflow/core/kernels/data/generator_dataset_op.cc:103] Error occurred when finalizing GeneratorDataset iterator: Cancelled: Operation was cancelled
Completed epoch 4. Saving weights...
Calculating validation losses...
Validation step 0 ...
Validation losses for epoch: 4 : Loss paf 63.838680267333984, Loss heatmap 25.57462501525879, Total loss 184.18460083007812
Start processing epoch 5
2020-04-01 13:25:44.597267: W tensorflow/core/framework/op_kernel.cc:1643] Unknown: RuntimeError: This DataFlow is not reentrant!
Traceback (most recent call last):

File "/home/unreal/anaconda3/envs/rahul_2.0/lib/python3.6/site-packages/tensorflow_core/python/ops/script_ops.py", line 236, in call
ret = func(*args)

File "/home/unreal/anaconda3/envs/rahul_2.0/lib/python3.6/site-packages/tensorflow_core/python/data/ops/dataset_ops.py", line 789, in generator_py_func
values = next(generator_state.get_iterator(iterator_id))

File "/home/unreal/rahul/Documents/pose_tf/dataset/generators.py", line 73, in f
for i in df:

File "/home/unreal/anaconda3/envs/rahul_2.0/lib/python3.6/site-packages/tensorpack/dataflow/parallel_map.py", line 309, in iter
with self._guard, _zmq_catch_error(type(self).name):

File "/home/unreal/anaconda3/envs/rahul_2.0/lib/python3.6/site-packages/tensorpack/dataflow/base.py", line 36, in enter
raise threading.ThreadError("This DataFlow is not reentrant!")

RuntimeError: This DataFlow is not reentrant!