Python shelve module question -

Whether the Python Stell module is designed to ensure any security, to ensure that two processes have a file Not written in the same time?

The Shelve module uses a built-in database package (such as DBM, or BSWD).

says (my emphasis):

flat module does not support searching items for reading / writing (read multiple simultaneously) The records are safe.) When a program opens a shelf to write, no other program should be open to read or write. Unix file locking can be used to resolve this, but it is different from Unix versions and it requires the knowledge about the implementation of the database.

Conclusion: It depends on the OS and the underlying DB. To keep things portable, do not build on concurrency.