1. Python Interpreter
Python is an interpreted language, meaning your code isn’t directly compiled into machine code (binary) that a CPU can execute.
Instead, the Python interpreter reads and executes your code line by line, converting it into bytecode, an intermediate form.
Python's default interpreter is CPython, written in C, which is the most widely used and often what people refer to when they mention "Python."
2. Bytecode and the Python Virtual Machine (PVM)
When you run a Python program, the interpreter first compiles your source code (.py files) into bytecode (.pyc files). Bytecode is a lower-level, platform-independent representation of your code.
The Python Virtual Machine (PVM) then reads this bytecode and executes it. This step is abstracted from the user, so you don’t need to think about it while coding, but it's good to know that Python translates your code in stages.
3. Memory Management
Python has an automatic memory management system that handles allocating and deallocating memory to store objects like variables and functions.
Garbage collection in Python clears up unused objects from memory to free up resources. It uses a mechanism called reference counting, tracking how many references exist for each object. When the count goes to zero (i.e., no references are pointing to the object), Python clears it from memory.
4. Global Interpreter Lock (GIL)
Python has a Global Interpreter Lock (GIL) in CPython, which restricts the execution of multiple threads at once.
This can be a bottleneck in CPU-bound tasks (like mathematical computations) because only one thread executes Python bytecode at a time.
However, GIL isn’t a big concern in I/O-bound programs, like web servers, where waiting on data is more frequent than computation. Libraries like NumPy and multiprocessing can help bypass the GIL for parallel processing needs.
5. Modules and Import System
Python code is modular, which means you can break it down into modules (separate .py files).
The
import
statement loads these modules into your program. Python checks for imported modules in specific directories, which it stores in thesys.path
variable.
6. Data Structures in Python
Python has built-in data structures like lists, tuples, dictionaries, and sets, which are highly optimized and easy to use.
Understanding how these data structures work internally (e.g., dictionaries using hash tables) can help you choose the most efficient structure for your needs.
7. Object-Oriented Design
Python supports object-oriented programming (OOP), allowing you to define classes and create objects, making your code more modular and reusable.
In Python, almost everything is an object, even functions and types. This approach makes it flexible and powerful, but it’s good to understand that Python is built around objects to design programs effectively.
8. Error Handling and Exceptions
- Python uses exceptions to handle errors. Rather than crashing, Python programs can "catch" exceptions using
try-except
blocks, allowing you to handle errors gracefully and keep the program running.