Python Virtual Machine (PVM): How It Runs Your Code

Probably you have heard that Python is one of the most versatile and commonly used programming languages. But have you wondered how since it does not seem to require any compiling before execution? Well, the answer is not that difficult: it goes through a very intricate compilation and interpretation process. So, when you write code in Python, it gets compiled to byte code and later gets into interpretation by the Virtual Machine—the Python Virtual Machine (PVM). In this, the role of PVM, the role that byte code plays, and the purpose of the pycache directory are described in detail within the explanation of Python's execution model.

What is the Python Virtual Machine (PVM)?
The Python Virtual Machine (PVM) is the runtime engine that executes Python byte code. It forms a loop interpreting and executing byte code instructions on the host machine. The PVM makes up the rest of the Python interpreter, actually executing your Python programs properly and effectively in varied environments.

How Python Program Execution Works: From Source Code to PVM Code Writing: You write your code in a .py file. This is the source code that a human may read, for it would be a plain text format.

Compiling to Byte Code When you run your Python script, the Python interpreter compiles your source code into byte code. Byte code is an intermediate, lower-level form of your source code, and it is platform-independent. The files containing byte code will have names ending in .pyc and are saved in the pycache directory.

Execution via PVM The compiled byte code is loaded onto the PVM. PVM interprets and executes all the byte code instructions—executing the required operation in the host machine.

Direct Interpretation and pycache The PVM is equipped with muscles to interpret and execute the Python scripts directly. While the execution of a Python script is taking place, PVM is also compiling the file to byte code on the fly. If a script imports other modules, the PVM checks the build directory for already existing byte code files. It finds the byte code it uses to hasten the execution of the modules. Otherwise, the imported modules are compiled into byte code by the PVM and saved into the build directory for further and future reference.

Why is pycache Important?
The pycache directory is kept to enhance the performance of Python programs by saving the compiled byte code of the modules. This caching mechanism saves the overhead of recompiling the modules each time they are imported and makes the program run relatively faster, especially on projects with many imports and dependencies.

Conclusion Python Virtual Machine is the base software in the Python execution model, which interprets and executes the Bytecodes. This knowledge would also make the developers fall in love with the efficiency, flexibility, the PVM, byte code, and the directory pycache. Besides deepening insight into the internal process of Python, it allows optimization of performance for Python applications.