BrokenPipeError in Lesson 12 notebook 7-seq2seq-translation.ipynb

[jcatanza]

Under my Windows 10 64-bit system, the command

xb,yb = next(iter(data.valid_dl))

in the section labeled "Our Model"

fails with

---

BrokenPipeError Traceback (most recent call last) in ----> 1 xb,yb = next(iter(data.valid_dl))

~\Anaconda3\envs\fastai\lib\site-packages\fastai\basic_data.py in iter(self) 73 def iter(self): 74 "Process and returns items from DataLoader." ---> 75 for b in self.dl: yield self.proc_batch(b) 76 77 @classmethod

~\Anaconda3\envs\fastai\lib\site-packages\torch\utils\data\dataloader.py in iter(self) 276 return _SingleProcessDataLoaderIter(self) 277 else: --> 278 return _MultiProcessingDataLoaderIter(self) 279 280 @property

~\Anaconda3\envs\fastai\lib\site-packages\torch\utils\data\dataloader.py in init(self, loader) 680 # before it starts, and del tries to join but will get: 681 # AssertionError: can only join a started process. --> 682 w.start() 683 self.index_queues.append(index_queue) 684 self.workers.append(w)

~\Anaconda3\envs\fastai\lib\multiprocessing\process.py in start(self) 110 'daemonic processes are not allowed to have children' 111 _cleanup() --> 112 self._popen = self._Popen(self) 113 self._sentinel = self._popen.sentinel 114 # Avoid a refcycle if the target function holds an indirect

~\Anaconda3\envs\fastai\lib\multiprocessing\context.py in _Popen(process_obj) 221 @staticmethod 222 def _Popen(process_obj): --> 223 return _default_context.get_context().Process._Popen(process_obj) 224 225 class DefaultContext(BaseContext):

~\Anaconda3\envs\fastai\lib\multiprocessing\context.py in _Popen(process_obj) 320 def _Popen(process_obj): 321 from .popen_spawn_win32 import Popen --> 322 return Popen(process_obj) 323 324 class SpawnContext(BaseContext):

~\Anaconda3\envs\fastai\lib\multiprocessing\popen_spawn_win32.py in init(self, process_obj) 87 try: 88 reduction.dump(prep_data, to_child) ---> 89 reduction.dump(process_obj, to_child) 90 finally: 91 set_spawning_popen(None)

~\Anaconda3\envs\fastai\lib\multiprocessing\reduction.py in dump(obj, file, protocol) 58 def dump(obj, file, protocol=None): 59 '''Replacement for pickle.dump() using ForkingPickler.''' ---> 60 ForkingPickler(file, protocol).dump(obj) 61 62 #

BrokenPipeError: [Errno 32] Broken pipe

[kashyap91]

Adding num_workers here - data = src.databunch(num_workers = 0) - is a workaround I tried. However - 1)The learn.lr_find() completes in under 15 seconds without the progress bar crossing 2%. 2)I also find input[x],targets[x].outputs[x] returning the same record for any value of x.

I am unsure if these issues are related to the BrokenPipeError and this workaround.