Error trying to pickle function when using multiple cpus to load data

[rphellan]

I get the error below when I run pretrain.py with the option --cpus 16

_pickle.PicklingError: Can't pickle <function <lambda> at 0x000001D39F94FDC0>: attribute lookup <lambda> on auxiliaries.finetune failed

The code works when I include the option --cpus 0, but I am not sure if this slows down how fast the data is loaded because not all possible CPUs are used.