Stop user from running malicious python code in online compilers

Question

I am developing an online compiler wherein user can run python code.My requirement is to run that python code on server side with exec. So I researched on how can I completely eliminate some user running malicious python code and most of the sites suggested this -

1. built-ins disabled
2. Ptrace and chroot jail
3. Sandboxing/VM

But if I store a list of blacklisted commands e.g - ["exec","os","subprocess"] and check the string code for presence of any blacklisted commands and discard it on client side as well as server side then doesn't it solve the problem?