使用进程池统计指定范围内的素数个数 30

以下是使用进程池统计指定范围内的素数个数的示例代码：

from multiprocessing import Pool

def is_prime(num):
    if num < 2:
        return False
    for i in range(2, int(num ** 0.5) + 1):
        if num % i == 0:
            return False
    return True

def count_primes(start, end):
    count = 0
    for num in range(start, end):
        if is_prime(num):
            count += 1
    return count

if __name__ == '__main__':
    num_processes = 4 # 设置进程池大小
    start = 2 # 范围起始值
    end = 100000 # 范围结束值
    pool = Pool(num_processes)
    chunk_size = (end - start) // num_processes # 每个进程处理的数据量
    results = []
    for i in range(num_processes):
        chunk_start = start + i * chunk_size
        chunk_end = chunk_start + chunk_size
        if i == num_processes - 1:
            chunk_end = end
        results.append(pool.apply_async(count_primes, args=(chunk_start, chunk_end)))
    pool.close()
    pool.join()
    total_count = 0
    for result in results:
        total_count += result.get()
    print(f'Total number of primes between {start} and {end}: {total_count}')

在上面的代码中，我们定义了两个函数：`is_prime`和`count_primes`。`is_prime`函数用于判断一个数是否为素数，`count_primes`函数用于在指定范围内统计素数的个数。然后我们在`main`函数中使用进程池来并行执行`count_primes`函数，将指定范围分成若干个小范围，每个进程处理一个小范围的数据。最后将所有进程的结果累加起来，得到指定范围内素数的总个数。