What is single-threading?

Single-threading is a program execution model where only one thread of commands is executed at a time.

Main characteristics:

• Sequential execution: Tasks are executed strictly one after another.
• Simplicity: Easier to develop and debug, as there is no need for synchronization of access to shared resources.
• Blocking: A long-running operation can "block" the execution of the entire program, waiting for its completion.

Example in Python:

# Example of single-threaded execution
import time

def task1():
    print("Task 1 started")
    time.sleep(2)
    print("Task 1 completed")

def task2():
    print("Task 2 started")
    time.sleep(1)
    print("Task 2 completed")

task1()
task2()

In this example, task2 will not start executing until task1 finishes.

Used in cases where:

• The program does not perform resource-intensive input/output operations or long computations in a loop.
• Simplicity of implementation is important.
• The program does not require real-time responsiveness during long tasks.

Comparison with multithreading:

Single-threading	Multithreading
One thread of execution	Multiple threads of execution
Sequential task execution	Parallel (or pseudo-parallel) task execution
Simpler to implement and debug	More complex to implement and debug
Easily blocked by long operations	Handles long operations better without blocking the entire process
Limited performance on multi-core processors for CPU-bound tasks	Allows utilizing multi-core processors for CPU-bound tasks (with GIL limitations in CPython)