Threads Overview

Learn what a Python thread is, how MainThread differs from a child thread, and why a thread is one flow of control inside a program.

Example

import threading

print(threading.current_thread().name)
print(threading.active_count())

The name is MainThread. The count is 1, because no child thread has been started. Later lessons call Thread.start(). This browser playground cannot start a second operating-system thread, so those pages run the same function on MainThread and print that fact.

Key takeaways

• A thread is a flow of control
• MainThread is the default flow, created when the program starts
• A child thread runs a function or a method
• One flow is sequential; extra child flows are the thread-based style
• A thread is lighter than starting a whole new process for the same small task
• Next: Function Threads — point Thread at a function and call start()