concurrent error

[l1ghtyagam1Jin]

raise self._exception

concurrent.futures.process.BrokenProcessPool: A process in the process pool was terminated abruptly while the future was running or pending.

This only happens when I try to parse some huge pdf files and using the conver_single_pdf function. It's all good when I tried with some 20 pages files and they are totally fine or using command line in terminal with huge pdf files.