Mastering Python’s mmap Module

Introduction to Python’s mmap Module

Python’s mmap module allows you to create memory-mapped files. This is particularly useful when you want to manipulate large files without loading the entire file into memory. Memory-mapped files are used for accessing small segments of large files on disk, without reading the entire file into memory.

Creating a Memory-Mapped File

To create a memory-mapped file, we use the mmap() function from the mmap module. Here is an example:

import mmap
with open('file.txt', 'r+b') as f:
    mmapped_file = mmap.mmap(f.fileno(), 0)

Reading and Writing Operations

Once the file is memory-mapped, you can perform read and write operations on it just like a regular file. Here is an example:

# Write to the file
mmapped_file.write(b'Hello World')
# Read from the file
mmapped_file.seek(0)
print(mmapped_file.read(11))

Handling Large Files

When working with large files, it’s important to handle them carefully to avoid memory issues. Always ensure to close the memory-mapped file once you’re done with it. This can be done using the close() method:

mmapped_file.close()

Conclusion

In conclusion, Python’s mmap module is a powerful tool for handling large files efficiently. It allows you to perform read and write operations on files without loading them entirely into memory, thus saving memory resources. However, it’s important to handle these files carefully to avoid memory issues.