from concurrent.futures import ThreadPoolExecutor, ProcessPoolExecutor

def get_pickled_string():
    import pickle
    from decimal import Decimal
    d = Decimal(1000)
    import numpy as np
    return pickle.dumps((d, np.float32))

def task(d):
    import pickle
    o = pickle._loads(d)

    return o

# Use a separate process to make the pickled bytes
# without importing the modules into our interpreter
with ProcessPoolExecutor() as pexecutor:
    f = pexecutor.submit(get_pickled_string)
    pickled_d = f.result()
    import sys
    assert "decimal" not in sys.modules


with ThreadPoolExecutor(max_workers=16) as executor:
    fs = [executor.submit(task, pickled_d)
          for i in range(1000)]

    # also do it here
    print(task(pickled_d))
    print([f.result() for f in fs])