Python Multi-Processing - Spawns只有两个进程

Question

我有一个python代码，需要对大约1MM的行进行一些处理。我们正在使用python的多处理模块

from multiprocessing import Pool

    rows_per_workload = 250000
    num_loads = math.ceil(data_df.shape[0]/float(rows_per_workload))
    agents =num_loads
    print ('Num Loads ', num_loads , ' DF Shape ', data_df.shape[0])
    split_df = np.array_split(data_df, num_loads) # List of DFs

    with Pool(processes=agents) as pool:
            result = pool.starmap(func=work,iterable=zip(split_df, [skey_data, skey_data]))
            result = pandas.concat(result)

def work(argdata, argmaster):
    print('parent process:', os.getppid())
    print('process id:', os.getpid())

即使我们期望从这一行产生4个进程     with Pool(processes=agents) as pool:我们只看到2个进程。当我运行此代码时，我们只看到两个PID

parent process: 19652
process id: 12936
parent process: 19652
process id: 14836

我错过了什么..

此致

巴拉