recover pickled data: pickle data was truncated

[iMath]

Normally, the shelve data should be read and write by only one process at a time, but unfortunately it was simultaneously read and write by two processes, thus corrupted it. Is there any way to recover all data in it ? Currently I just get "pickle data was truncated" exception after reading a portion of the data?

Data and code here :https://drive.google.com/file/d/137nJFc1TvOge88EjzhnFX9bXg6vd0RYQ/view?usp=sharing