# Can't pickle local object 'DataLoader.\_\_init\_\_.\.\' **URL:** \ **Category:** vision\ **Created:** [December 11, 2018, 12:03pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857 "2018-12-11T12:03:49Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![albanD](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/alband/32/215_2.png) [@albanD](https://discuss.pytorch.org/u/albanD)\ **Post date:** [September 10, 2020, 7:00pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/21 "2020-09-10T19:00:01Z")
Do you get a different error after removing the lambda? Because the error is explicitly about a lambda which cannot be serialized. ---
**Author:** ![asura](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/asura/32/28647_2.png) [@asura](https://discuss.pytorch.org/u/asura)\ **Post date:** [September 10, 2020, 8:08pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/22 "2020-09-10T20:08:26Z")
@albanD No, it’s the same error. I have also made sure that no lambda functions remain in the code. ---
**Author:** ![albanD](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/alband/32/215_2.png) [@albanD](https://discuss.pytorch.org/u/albanD)\ **Post date:** [September 10, 2020, 9:39pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/23 "2020-09-10T21:39:38Z")
If the error still points at a lambda function. Then you have one left. If it points to something else, you can share it here so that we can take a look. ---
**Author:** ![asura](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/asura/32/28647_2.png) [@asura](https://discuss.pytorch.org/u/asura)\ **Post date:** [September 11, 2020, 3:41am UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/24 "2020-09-11T03:41:31Z")
@albanD I have reproduced the error here : [https://colab.research.google.com/drive/10Zxe40Tl14fWAaCAYg1fgQA13hHIiBo\_?usp=sharing](https://colab.research.google.com/drive/10Zxe40Tl14fWAaCAYg1fgQA13hHIiBo_?usp=sharing) The error is : ```auto AttributeError Traceback (most recent call last) in () 168 if __name__ == ' __main__': 169 t1 = time.time() --> 170 main() 171 print("Time taken :", time.time() - t1) 5 frames in main(ways, shots, meta_lr, fast_lr, meta_batch_size, adaptation_steps, num_iterations, cuda, seed) 126 args = [maml, tasksets] 127 with Pool(4) as pool: --> 128 values = pool.map(partial(ParallelTasks, args), list(range(meta_batch_size))) 129 130 #for i in range(values): /usr/lib/python3.6/multiprocessing/pool.py in map(self, func, iterable, chunksize) 264 in a list that is returned. 265 ''' --> 266 return self._map_async(func, iterable, mapstar, chunksize).get() 267 268 def starmap(self, func, iterable, chunksize=None): /usr/lib/python3.6/multiprocessing/pool.py in get(self, timeout) 642 return self._value 643 else: --> 644 raise self._value 645 646 def _set(self, i, obj): /usr/lib/python3.6/multiprocessing/pool.py in _handle_tasks(taskqueue, put, outqueue, pool, cache) 422 break 423 try: --> 424 put(task) 425 except Exception as e: 426 job, idx = task[:2] /usr/lib/python3.6/multiprocessing/connection.py in send(self, obj) 204 self._check_closed() 205 self._check_writable() --> 206 self._send_bytes(_ForkingPickler.dumps(obj)) 207 208 def recv_bytes(self, maxlength=None): /usr/lib/python3.6/multiprocessing/reduction.py in dumps(cls, obj, protocol) 49 def dumps(cls, obj, protocol=None): 50 buf = io.BytesIO() ---> 51 cls(buf, protocol).dump(obj) 52 return buf.getbuffer() 53 AttributeError: Can't pickle local object 'omniglot_tasksets..' ``` ---
**Author:** ![asura](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/asura/32/28647_2.png) [@asura](https://discuss.pytorch.org/u/asura)\ **Post date:** [September 11, 2020, 5:15am UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/25 "2020-09-11T05:15:11Z")
@albanD The same error is seen in Linux environment too. ---
**Author:** ![albanD](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/alband/32/215_2.png) [@albanD](https://discuss.pytorch.org/u/albanD)\ **Post date:** [September 12, 2020, 3:06pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/26 "2020-09-12T15:06:38Z")
GIven the names, I guess the problem is that the taskset you’re using cannot be serialized. And so you cannot use it in the process Pool. You can either unpack these in a different object that you can serialize or change the libary to make the taskset serializable. ---
**Author:** ![asura](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/asura/32/28647_2.png) [@asura](https://discuss.pytorch.org/u/asura)\ **Post date:** [September 12, 2020, 5:13pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/27 "2020-09-12T17:13:20Z")
Ah ok, I will try that approach. That’s for the insights @albanD. 😁 That might be the case it seems. ---
**Author:** ![asura](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/asura/32/28647_2.png) [@asura](https://discuss.pytorch.org/u/asura)\ **Post date:** [September 18, 2020, 1:05pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/28 "2020-09-18T13:05:27Z")
I will post my solution here in case someone also faces the same error. As @albanD said, the error was because dataset couldn’t be serialized. I used `import dill` and the error was solved. In case someone is still facing issue, they can try this too `from pathos.multiprocessing import ProcessingPool as Pool`. 🙂 ---
**Author:** ![lillepeder](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/lillepeder/32/29921_2.png) [@lillepeder](https://discuss.pytorch.org/u/lillepeder)\ **Post date:** [October 16, 2020, 3:32pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/29 "2020-10-16T15:32:59Z")
Dear @Asura, in which file(s) specifically did you include the `import dill` statement? ---
**Author:** ![asura](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/asura/32/28647_2.png) [@asura](https://discuss.pytorch.org/u/asura)\ **Post date:** [October 16, 2020, 5:14pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/30 "2020-10-16T17:14:54Z")
Hi @lillepeder, I was using Colab and added it in the top cell. But, I suppose it will work as long as you add it the file where serialization is taking place. Otherwise, try the later approach, `pathos` already has `dill`, so you won’t need to figure out where to import it specifically. ---
**Author:** ![lillepeder](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/lillepeder/32/29921_2.png) [@lillepeder](https://discuss.pytorch.org/u/lillepeder)\ **Post date:** [October 16, 2020, 5:17pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/31 "2020-10-16T17:17:22Z")
I found an alternative solution: pass `num_workers=0` into the DataLoader, in case anyone else get a similar problem! A little slower, but it overcomes the pickling issue. ---
**Author:** ![lillepeder](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/lillepeder/32/29921_2.png) [@lillepeder](https://discuss.pytorch.org/u/lillepeder)\ **Post date:** [October 16, 2020, 5:18pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/32 "2020-10-16T17:18:34Z")
Thank you for the quick reply, but I seem to have solved it for now with `num_workers=0` 🙂 ---
**Author:** ![Brando\_Miranda](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/brando_miranda/32/14355_2.png) [@Brando\_Miranda](https://discuss.pytorch.org/u/Brando_Miranda)\ **Post date:** [November 3, 2020, 9:14pm UTC](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857/33 "2020-11-03T21:14:46Z")
I also had this error in my mac with this transform: ```auto self.train_transform = transforms.Compose([ lambda x: Image.fromarray(x), transforms.RandomCrop(84, padding=8), transforms.ColorJitter(brightness=0.4, contrast=0.4, saturation=0.4), transforms.RandomHorizontalFlip(), lambda x: np.asarray(x), transforms.ToTensor(), self.normalize ]) ``` I don’t understand why there is pickling going on…seems weird. But I will try to change the things above to non-lambdas. I will first try: ```auto lambda x: Image.fromarray(x) ---> Image.fromarray ``` hopefully that works. * * * **yes it did work for me.** [Previous page](https://discuss.pytorch.org/t/cant-pickle-local-object-dataloader-init-locals-lambda/31857.md?page=1)