Hướng dẫn can you thread within a thread in python? - bạn có thể xâu chuỗi trong một chuỗi trong python không?

Chủ đề là gì

Cách tạo chủ đề và chờ chúng hoàn thành

Cách sử dụng

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

Làm thế nào để tránh điều kiện cuộc đua

Cách sử dụng các công cụ phổ biến mà Python

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

Bài viết này giả định rằng bạn đã có những điều cơ bản của Python và bạn sử dụng ít nhất phiên bản 3.6 để chạy các ví dụ. Nếu bạn cần bồi dưỡng, bạn có thể bắt đầu với các đường dẫn học tập Python và tăng tốc.

Nếu bạn không chắc chắn nếu bạn muốn sử dụng Python

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

Tất cả các nguồn được sử dụng trong hướng dẫn này đều có sẵn cho bạn trong repo Python GitHub thực sự.

Kiến trúc chương trình của bạn để sử dụng luồng cũng có thể cung cấp lợi ích trong thiết kế rõ ràng. Hầu hết các ví dụ mà bạn sẽ tìm hiểu trong hướng dẫn này không nhất thiết sẽ chạy nhanh hơn vì chúng sử dụng các chủ đề. Sử dụng luồng trong chúng giúp làm cho thiết kế sạch hơn và dễ lý luận hơn.

Vì vậy, hãy để Lôi ngừng nói về việc xâu chuỗi và bắt đầu sử dụng nó!

Bắt đầu một chủ đề

Bây giờ, bạn đã có một ý tưởng về một chủ đề là gì, hãy để học cách tạo ra một chủ đề. Thư viện tiêu chuẩn Python cung cấp

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

Để bắt đầu một luồng riêng biệt, bạn tạo một thể hiện

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Nếu bạn nhìn xung quanh các câu lệnh ghi nhật ký, bạn có thể thấy rằng phần

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

x = threading.Thread(target=thread_function, args=(1,))
x.start()

Khi bạn tạo

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

Đối với bài viết này, bạn sẽ sử dụng các số nguyên tuần tự làm tên cho các chủ đề của bạn. Có

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

Khi bạn chạy chương trình này như hiện tại (với dòng hai mươi nhận xét), đầu ra sẽ trông như thế này:

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

Bạn sẽ nhận thấy rằng

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

import concurrent.futures

# [rest of code]

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    with concurrent.futures.ThreadPoolExecutor(max_workers=3) as executor:
        executor.map(thread_function, range(3))

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

Làm việc với nhiều chủ đề

Mã ví dụ cho đến nay chỉ hoạt động với hai luồng: luồng chính và một luồng bạn bắt đầu với đối tượng

import concurrent.futures

# [rest of code]

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    with concurrent.futures.ThreadPoolExecutor(max_workers=3) as executor:
        executor.map(thread_function, range(3))

Thông thường, bạn sẽ muốn bắt đầu một số chủ đề và yêu cầu chúng làm công việc thú vị. Hãy bắt đầu bằng cách nhìn vào cách làm điều đó khó hơn, và sau đó bạn sẽ chuyển sang một phương pháp dễ dàng hơn.

Cách khó hơn để bắt đầu nhiều luồng là cách mà bạn đã biết:

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

Mã này sử dụng cùng một cơ chế mà bạn đã thấy ở trên để bắt đầu một luồng, tạo một đối tượng

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

x = threading.Thread(target=thread_function, args=(1,), daemon=True)

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

Chạy mã này nhiều lần có thể sẽ tạo ra một số kết quả thú vị. Ở đây, một ví dụ đầu ra từ máy của tôi:

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

Nếu bạn đi qua đầu ra một cách cẩn thận, bạn sẽ thấy cả ba chủ đề bắt đầu theo thứ tự bạn có thể mong đợi, nhưng trong trường hợp này, chúng kết thúc theo thứ tự ngược lại! Nhiều lần chạy sẽ tạo ra các thứ tự khác nhau. Tìm tin nhắn

import concurrent.futures

# [rest of code]

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    with concurrent.futures.ThreadPoolExecutor(max_workers=3) as executor:
        executor.map(thread_function, range(3))

Thứ tự mà các luồng được chạy được xác định bởi hệ điều hành và có thể khá khó dự đoán. Nó có thể (và có thể sẽ) thay đổi từ chạy đến chạy, vì vậy bạn cần nhận thức được điều đó khi bạn thiết kế các thuật toán sử dụng luồng.

May mắn thay, Python cung cấp cho bạn một số nguyên thủy mà bạn sẽ xem xét sau này để giúp phối hợp các luồng và khiến chúng chạy cùng nhau. Trước đó, hãy để Lôi nhìn vào cách làm cho việc quản lý một nhóm các chủ đề dễ dàng hơn một chút.

Sử dụng $ ./single_thread.py Main : before creating thread Main : before running thread Thread 1: starting Main : wait for the thread to finish Main : all done Thread 1: finishing 7

Có một cách dễ dàng hơn để bắt đầu một nhóm các chủ đề so với cái bạn thấy ở trên. Nó được gọi là

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

$ ./executor.py
Thread 0: starting
Thread 1: starting
Thread 2: starting
Thread 1: finishing
Thread 0: finishing
Thread 2: finishing

Cách dễ nhất để tạo nó là một người quản lý bối cảnh, sử dụng tuyên bố

$ ./executor.py
Thread 0: starting
Thread 1: starting
Thread 2: starting
Thread 1: finishing
Thread 0: finishing
Thread 2: finishing

Tại đây,

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

import concurrent.futures

# [rest of code]

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    with concurrent.futures.ThreadPoolExecutor(max_workers=3) as executor:
        executor.map(thread_function, range(3))

Mã tạo ra

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

$ ./executor.py
Thread 0: starting
Thread 1: starting
Thread 2: starting
Thread 1: finishing
Thread 0: finishing
Thread 2: finishing

$ ./executor.py
Thread 0: starting
Thread 1: starting
Thread 2: starting
Thread 1: finishing
Thread 0: finishing
Thread 2: finishing

Phần cuối của khối

$ ./executor.py
Thread 0: starting
Thread 1: starting
Thread 2: starting
Thread 1: finishing
Thread 0: finishing
Thread 2: finishing

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

$ ./multiple_threads.py
Main    : create and start thread 0.
Thread 0: starting
Main    : create and start thread 1.
Thread 1: starting
Main    : create and start thread 2.
Thread 2: starting
Main    : before joining thread 0.
Thread 2: finishing
Thread 1: finishing
Thread 0: finishing
Main    : thread 0 done
Main    : before joining thread 1.
Main    : thread 1 done
Main    : before joining thread 2.
Main    : thread 2 done

Chạy mã ví dụ đã sửa của bạn sẽ tạo ra đầu ra trông như thế này:

$ ./executor.py
Thread 0: starting
Thread 1: starting
Thread 2: starting
Thread 1: finishing
Thread 0: finishing
Thread 2: finishing

Một lần nữa, hãy chú ý cách

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Điều kiện chủng tộc

Trước khi bạn chuyển sang một số tính năng khác được giấu trong Python

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

Khi bạn đã thấy một điều kiện cuộc đua là gì và nhìn vào một người xảy ra, bạn sẽ chuyển sang một số nguyên thủy được cung cấp bởi thư viện tiêu chuẩn để ngăn chặn các điều kiện chủng tộc xảy ra.

Điều kiện cuộc đua có thể xảy ra khi hai hoặc nhiều luồng truy cập một phần dữ liệu hoặc tài nguyên được chia sẻ. Trong ví dụ này, bạn sẽ tạo ra một điều kiện cuộc đua lớn xảy ra mọi lúc, nhưng lưu ý rằng hầu hết các điều kiện chủng tộc không rõ ràng như vậy. Thông thường, chúng chỉ xảy ra hiếm khi và chúng có thể tạo ra kết quả khó hiểu. Như bạn có thể tưởng tượng, điều này làm cho chúng khá khó để gỡ lỗi.

May mắn thay, điều kiện cuộc đua này sẽ xảy ra mỗi lần và bạn sẽ đi qua nó một cách chi tiết để giải thích những gì đang xảy ra.

Trong ví dụ này, bạn sẽ viết một lớp cập nhật cơ sở dữ liệu. Được rồi, bạn không thực sự sẽ có một cơ sở dữ liệu: bạn sẽ chỉ giả mạo nó, bởi vì đó không phải là điểm của bài viết này.

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Trong trường hợp này, đọc từ cơ sở dữ liệu chỉ có nghĩa là sao chép

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Đây là cách bạn sử dụng

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Chương trình tạo ra một

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Trong việc sử dụng ở trên,

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Vì mỗi luồng chạy

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

Bạn có thể đã mong đợi điều đó sẽ xảy ra, nhưng hãy để Lôi nhìn vào các chi tiết về những gì mà thực sự đang diễn ra ở đây, vì điều đó sẽ làm cho giải pháp cho vấn đề này dễ hiểu hơn.

Một chủ đề

Trước khi bạn đi sâu vào vấn đề này với hai chủ đề, hãy để Lùi lại và nói một chút về một số chi tiết về cách các chủ đề hoạt động.

Bạn đã giành chiến thắng khi đi sâu vào tất cả các chi tiết ở đây, vì điều đó không quan trọng ở cấp độ này. Chúng tôi cũng sẽ đơn giản hóa một vài điều theo cách mà giành được chính xác về mặt kỹ thuật nhưng sẽ cho bạn ý tưởng đúng về những gì đang xảy ra.

Khi bạn nói với

$ ./single_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done
Thread 1: finishing

7 của mình để chạy từng luồng, bạn sẽ cho nó biết chức năng nào sẽ chạy và những tham số nào sẽ truyền cho nó:

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

30.

Kết quả của điều này là mỗi luồng trong nhóm sẽ gọi

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

31. Lưu ý rằng

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

32 là một tham chiếu đến đối tượng

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

06 được tạo trong

import logging
import threading
import time

def thread_function(name):
    logging.info("Thread %s: starting", name)
    time.sleep(2)
    logging.info("Thread %s: finishing", name)

if __name__ == "__main__":
    format = "%(asctime)s: %(message)s"
    logging.basicConfig(format=format, level=logging.INFO,
                        datefmt="%H:%M:%S")

    threads = list()
    for index in range(3):
        logging.info("Main    : create and start thread %d.", index)
        x = threading.Thread(target=thread_function, args=(index,))
        threads.append(x)
        x.start()

    for index, thread in enumerate(threads):
        logging.info("Main    : before joining thread %d.", index)
        thread.join()
        logging.info("Main    : thread %d done", index)

6. Gọi

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08 trên đối tượng đó gọi một phương thức thể hiện trên đối tượng đó.

Mỗi luồng sẽ có một tham chiếu đến cùng một đối tượng

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

06,

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

32. Mỗi luồng cũng sẽ có một giá trị duy nhất,

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

22, để làm cho các câu lệnh ghi nhật ký dễ đọc hơn một chút:

Khi luồng bắt đầu chạy

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08, nó có phiên bản riêng của tất cả dữ liệu cục bộ cho chức năng. Trong trường hợp của

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08, đây là

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

41. Đây chắc chắn là một điều tốt. Nếu không, hai luồng chạy cùng một chức năng sẽ luôn gây nhầm lẫn cho nhau. Nó có nghĩa là tất cả các biến được phạm vi (hoặc cục bộ) đến một hàm đều an toàn.local to the function. In the case of

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08, this is

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

41. This is definitely a good thing. Otherwise, two threads running the same function would always confuse each other. It means that all variables that are scoped (or local) to a function are thread-safe.

Bây giờ bạn có thể bắt đầu đi qua những gì xảy ra nếu bạn chạy chương trình ở trên với một luồng duy nhất và một cuộc gọi đến

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08.

Hình ảnh bên dưới bước thông qua việc thực hiện

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08 nếu chỉ chạy một luồng. Câu lệnh được hiển thị ở bên trái theo sau là sơ đồ hiển thị các giá trị trong luồng

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

41 và được chia sẻ

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

27:

Sơ đồ được đặt ra để thời gian tăng khi bạn di chuyển từ trên xuống dưới. Nó bắt đầu khi

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

03 được tạo và kết thúc khi nó bị chấm dứt.

Khi

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

03 bắt đầu,

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

48 bằng không. Dòng mã đầu tiên trong phương thức,

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

49, sao chép giá trị 0 vào biến cục bộ. Tiếp theo, nó tăng giá trị của

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

41 với câu lệnh

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

51. Bạn có thể thấy

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

10 trong

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

03 được đặt thành một.

Tiếp theo

$ ./daemon_thread.py
Main    : before creating thread
Main    : before running thread
Thread 1: starting
Main    : wait for the thread to finish
Main    : all done

5 được gọi, làm cho tạm dừng luồng hiện tại và cho phép các luồng khác chạy. Vì chỉ có một chủ đề trong ví dụ này, điều này không có hiệu lực.

Khi

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

03 thức dậy và tiếp tục, nó sao chép giá trị mới từ

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

41 đến

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

48, và sau đó luồng hoàn tất. Bạn có thể thấy rằng

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

27 được đặt thành một.

Càng xa càng tốt. Bạn đã chạy

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

08 một lần và

 1import logging
 2import threading
 3import time
 4
 5def thread_function(name):
 6    logging.info("Thread %s: starting", name)
 7    time.sleep(2)
 8    logging.info("Thread %s: finishing", name)
 9
10if __name__ == "__main__":
11    format = "%(asctime)s: %(message)s"
12    logging.basicConfig(format=format, level=logging.INFO,
13                        datefmt="%H:%M:%S")
14
15    logging.info("Main    : before creating thread")
16    x = threading.Thread(target=thread_function, args=(1,))
17    logging.info("Main    : before running thread")
18    x.start()
19    logging.info("Main    : wait for the thread to finish")
20    # x.join()
21    logging.info("Main    : all done")

48 đã được tăng lên một.