Lære Threads vs. Processes in Python | Introduction to Concurrency

Understanding the distinction between threads and processes is crucial when you need to write concurrent programs in Python. Both threads and processes enable your code to perform multiple tasks seemingly at the same time, but they do so in fundamentally different ways.

Threads are lightweight units of execution that run within the same process. This means threads share the same memory space and resources, which makes it easy for them to communicate and share data. However, this shared memory can also lead to issues such as data corruption if multiple threads try to modify the same data at once. Threads are best suited for tasks that are I/O-bound, such as waiting for user input, reading from files, or downloading data from the internet. Because threads have less overhead than processes, starting and switching between them is faster and uses less memory.

Processes, on the other hand, are independent units of execution. Each process has its own memory space, which means processes do not share data directly. This separation makes processes more robust and less likely to interfere with each other, but it also means that sharing data between processes is more complex and often requires specialized mechanisms like queues or pipes. Processes are ideal for CPU-bound tasks that require intensive computation, such as data analysis or image processing, because each process can run on a separate CPU core without being limited by Python's Global Interpreter Lock (GIL). However, processes have higher overhead than threads, both in terms of memory usage and the time it takes to start or stop them.

When deciding whether to use threads or processes in Python, consider the following:

Use threads when your program spends most of its time waiting for input/output operations and needs to share data easily between tasks;
Use processes when your program needs to perform heavy computations in parallel and can benefit from true multi-core execution, or when you need to isolate tasks from each other for safety or stability.


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import threading
import multiprocessing
import time

def thread_task():
    print("Thread starting")
    time.sleep(1)
    print("Thread finished")

def process_task():
    print("Process starting")
    time.sleep(1)
    print("Process finished")

# Create and start a thread
t = threading.Thread(target=thread_task)
t.start()
t.join()

# Create and start a process
p = multiprocessing.Process(target=process_task)
p.start()
p.join()

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When deciding whether to use threads or processes in Python, consider the following:

Use threads when your program spends most of its time waiting for input/output operations and needs to share data easily between tasks;
Use processes when your program needs to perform heavy computations in parallel and can benefit from true multi-core execution, or when you need to isolate tasks from each other for safety or stability.


              1234567891011121314151617181920212223
            
import threading
import multiprocessing
import time

def thread_task():
    print("Thread starting")
    time.sleep(1)
    print("Thread finished")

def process_task():
    print("Process starting")
    time.sleep(1)
    print("Process finished")

# Create and start a thread
t = threading.Thread(target=thread_task)
t.start()
t.join()

# Create and start a process
p = multiprocessing.Process(target=process_task)
p.start()
p.join()

Var alt klart?

Tak for dine kommentarer!

Sektion 1. Kapitel 2