Adventures in Machine Learning

Boost your Python performance with mmap memory mapping!

In computer science, memory management is an essential aspect of programming. When a program runs, it uses the computer’s physical memory to store data and instructions.

However, at times, the physical memory might not be enough, and the program needs to use the computer’s virtual memory or shared memory. In such scenarios, memory mapping plays a crucial role.

Memory Mapping:

Memory mapping is the process of mapping a file or a portion of it to the program’s address space. In other words, it allows the program to access the file data directly from the disk.

It means that the program does not have to read the data from the disk to the physical memory to manipulate it. The primary benefit of memory mapping is that it saves the program’s memory usage while avoiding the CPU overhead needed to move data between memory and disk.

Memory Management in a Computer:

A computer’s memory management system is responsible for allocating, de-allocating and managing the computer’s physical memory and virtual memory. It ensures that each program running on the computer gets the required amount of memory to function optimally.

The computer’s physical memory is finite and the programs are competing for a share of this limited resource. So, memory management system has an essential job of allocating memory to different programs efficiently.

How to use mmap function in Python? Python provides a built-in mmap module that allows memory mapping.

It is a powerful tool that enables file I/O directly to and from the disk. The mmap function creates a buffer object, which maps a file to memory.

The function parameters take a file descriptor, length, and an access argument. The access argument specifies whether the mapped memory will be read-only or read-write.

Using mmap for File I/O in Python:

The mmap function allows easy data transfer between the file and memory. When the memory-mapped file is updated, the file is updated automatically on disk.

Here are some of the essential things to know. Description of mmap function:

The mmap function creates a new memory map for a file or an existing memory map identified by the file descriptor fd.

The length parameter specifies the number of bytes to map from the file. The access parameter specifies the access mode of the memory map, which can have three values: ACCESS_READ, ACCESS_WRITE, and ACCESS_COPY.

How to write data to memory-mapped files? To write to a memory-mapped file, set the access privilege to ACCESS_WRITE.

Additionally, use the slice operator to access a particular index or range of items. The slice operator is familiar to Python users, and it is used to extract a specific portion of a python list.

How to access a certain portion of a file using mmap? Using the slice operator, it is possible to access a particular part of a memory-mapped file.

The slice operator can take two values, indicating the start and end indices to use. It is an efficient way to access different parts of the memory-mapped file.


Memory mapping is an essential aspect of computer programming. It allows programs to access data and instructions directly from the disk, avoiding repetitive I/O operations and saving on memory usage.

Python provides the mmap module for directly mapping files onto memory, and there is plenty of documentation available to support the process. By employing mmap, developers can make better use of the RAM in their computing systems, improving the performance of their applications and ultimately enhancing the user experience.

Advantages of using mmap in Python:

Pythons mmap module allows for the creation of memory-mapped files. This is the process of directly mapping a file to virtual memory so that the file contents can be accessed by user applications without requiring read or write operations to be performed by the system frequently.

When compared to traditional file I/O operations, memory-mapped files, using the mmap function, offer many performance improvements. Why use mmap in Python?

The principal advantage of using mmap in Python is performance. When a program reads or writes within a memory-mapped file, it avoids C library read and write operations that would make system calls otherwise.

This results in significant savings in processing time, allowing programs to run much faster than if reading and writing operations occurred without memory mapping.

Here are a few specific advantages of using mmap in Python:


Reduced disk I/O: Memory-mapped files reduce the incidence of disk I/O operations performed by the system, as noted earlier. This can result in more efficient program execution and reduced system load.

When performing applications that require heavy I/O operations, memory-mapped files contribute to an overall improvement in performance, making programs faster and more efficient. 2.

Convenience and ease-of-use: Memory-mapped files are an efficient solution for dealing with large data sets that need to be read multiple times throughout the lifetime of a program. If you load frequently-used data into virtual memory, you can skip the process of repeatedly shifting that data to and from disk A memory-mapped file can be treated like a regular file object, involving no additional overhead to use it, which means developers can quickly and efficiently apply it to their workflows.

3. Reduced memory usage: Memory-mapped files enable programs to complete data processing through the use of virtual memory, which reduces the actual memory usage of the system.

When working with large data files, this can have a significant impact on the system’s performance, helping to prevent the system from becoming overwhelmed with data while ensuring efficient execution of the program. 4.

Improved performance: By avoiding traditional file I/O operations and system calls and using in-memory operations, memory-mapped files can significantly improve the performance of programs that use them. This is especially true for programs that deal with large data sets as they are faster, smoother, and more efficient.

In conclusion:

Memory-mapping files with the mmap function provides many advantages for Python users dealing with large data sets. By making use of virtual memory, memory-mapped files significantly improve performance by reducing the frequency of traditional file I/O data operations, system calls and can greatly reduce the use of physical memory.

This represents a powerful tool in the developer toolkit for anyone looking to boost their systems performance while running data-intensive applications. Therefore, it is recommended that any developer looking to improve their Python programming and create more efficient algorithms make use of Pythons built-in mmap module when necessary to optimize their software.

In conclusion, memory mapping using Python’s mmap function offers several advantages over traditional file I/O operations. With mmap, memory access is direct, and disk I/O operations are reduced, which results in improved performance.

Memory-mapped files are efficient, easy to use, reduce memory usage, and significantly improve program execution when handling large data sets. Memory mapping with mmap is a valuable tool for any developer dealing with a significant amount of data and is an excellent technique for optimizing the performance of Python applications.

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