multiprocessing模块详解 - Python多进程编程指南

from multiprocessing import Process, current_process, cpu_count

# Process 构造函数
process = Process(target=函数名, args=(参数1, 参数2, ...), name='进程名', daemon=False)

# 参数说明：
# target: 进程要执行的函数（不加括号）
# args:   传递给 target 的位置参数元组
# name:   进程名称，便于调试
# daemon: 是否为守护进程（True表示父进程退出时子进程自动终止）

# 常用属性和方法：
# process.start()    — 启动进程
# process.join(timeout=None) — 等待进程结束
# process.terminate() — 强制终止进程
# process.is_alive()  — 检查进程是否存活
# process.pid         — 获取进程ID
# current_process().name — 获取当前进程名
# cpu_count()        — 获取CPU核心数

from multiprocessing import Process
import time

def worker(name, delay):
    """工作进程函数"""
    print(f"进程 {name} 启动")
    time.sleep(delay)
    print(f"进程 {name} 完成")

if __name__ == '__main__':
    # 创建进程对象
    p1 = Process(target=worker, args=('A', 2), name='Worker-A')
    p2 = Process(target=worker, args=('B', 1), name='Worker-B')
    
    # 启动进程
    p1.start()
    p2.start()
    
    # 等待进程结束
    p1.join()
    p2.join()
    
    print("所有子进程已结束")

from multiprocessing import Process
import time

def compute_task(task_id):
    print(f"任务 {task_id} 开始执行")
    time.sleep(1)
    print(f"任务 {task_id} 完成")

if __name__ == '__main__':
    processes = []
    
    # 批量创建并启动
    for i in range(5):
        p = Process(target=compute_task, args=(i,))
        processes.append(p)
        p.start()
    
    # 统一等待所有进程结束
    for p in processes:
        p.join()
    
    print("所有任务执行完毕")

from multiprocessing import Process, cpu_count
import time
import math

def calculate_primes(n):
    """计算前n个素数（CPU密集型）"""
    primes = []
    num = 2
    while len(primes) < n:
        is_prime = True
        for i in range(2, int(math.sqrt(num)) + 1):
            if num % i == 0:
                is_prime = False
                break
        if is_prime:
            primes.append(num)
        num += 1
    print(f"找到 {len(primes)} 个素数")

if __name__ == '__main__':
    start = time.time()
    
    # 使用多进程并行计算
    processes = []
    num_cores = cpu_count()
    print(f"CPU核心数: {num_cores}")
    
    for i in range(num_cores):
        p = Process(target=calculate_primes, args=(50000,))
        processes.append(p)
        p.start()
    
    for p in processes:
        p.join()
    
    print(f"多进程耗时: {time.time() - start:.2f} 秒")

from multiprocessing import Process

# 全局变量
counter = 0

def increment():
    global counter
    for _ in range(100000):
        counter += 1
    print(f"子进程 counter = {counter}")

if __name__ == '__main__':
    p1 = Process(target=increment)
    p2 = Process(target=increment)
    
    p1.start()
    p2.start()
    p1.join()
    p2.join()
    
    print(f"主进程 counter = {counter}")
    # 输出：主进程 counter = 0
    # 因为每个进程都有自己的 counter 副本，互不影响