text: Title: OSError when << use_memory_fs=True>>
  Body: ```
  %load_ext autoreload
  %autoreload 2
  import pandas as pd
  import time
  from pandarallel import pandarallel
  import math
  import numpy as np
  ```
  
  ```
  pandarallel.initialize(nb_workers=60,progress_bar=True)
  
  
  df_size = int(5e7)
  df = pd.DataFrame(dict(a=np.random.rand(df_size) + 1))
  df.head()
  
  def func(x):
      return math.log10(math.sqrt(math.exp(x**2)))
  
  %%time
  df['b'] = df.a.parallel_map(func)
  ```
  
  ```
  ---------------------------------------------------------------------------
  OSError                                   Traceback (most recent call last)
  /opt/conda/lib/python3.6/site-packages/pandarallel/pandarallel.py in get_workers_args(use_memory_fs, nb_workers, progress_bar, chunks, worker_meta_args, queue, func, args, kwargs)
      254                 dump_and_get_lenght(chunk, input_file)
  --> 255                 for chunk, input_file in zip(chunks, input_files)
      256             ]
  
  /opt/conda/lib/python3.6/site-packages/pandarallel/pandarallel.py in <listcomp>(.0)
      254                 dump_and_get_lenght(chunk, input_file)
  --> 255                 for chunk, input_file in zip(chunks, input_files)
      256             ]
  
  /opt/conda/lib/python3.6/site-packages/pandarallel/pandarallel.py in dump_and_get_lenght(chunk, input_file)
      243         with open(input_file.name, "wb") as file:
  --> 244             pickle.dump(chunk, file)
      245 
  
  OSError: [Errno 28] No space left on device
  
  During handling of the above exception, another exception occurred:
  
  OSError                                   Traceback (most recent call last)
  /usr/local/bin/kernel-launchers/python/scripts/launch_ipykernel.py in <module>
  
  /opt/conda/lib/python3.6/site-packages/pandarallel/pandarallel.py in closure(data, func, *args, **kwargs)
      425             func,
      426             args,
  --> 427             kwargs,
      428         )
      429         try:
  
  /opt/conda/lib/python3.6/site-packages/pandarallel/pandarallel.py in get_workers_args(use_memory_fs, nb_workers, progress_bar, chunks, worker_meta_args, queue, func, args, kwargs)
      270                 )
      271             )
  --> 272             raise OSError(msg)
      273 
      274         workers_args = [
  ```
  
  `OSError: It seems you use Memory File System and you don't have enough available space in `dev/shm`. You can either call pandarallel.initalize with `use_memory_fs=False`, or you can  increase the size of `dev/shm` as described here: https://stackoverflow.com/questions/58804022/how-to-resize-dev-shm .  Please also remove all files beginning with 'pandarallel_' in the `/dev/shm` directory. If you have troubles with your web browser, these troubles should deseapper after cleaning `/dev/shm`.`
  
  **Question**: I get error when I don't pass `use_memory_fs=False`. If I want to use memory how can I overcome this?