python：'open'阻止进程？

Question

我发现open用python阻塞了。这是我的代码

import concurrent.futures
import os
import time
import logging
logging.basicConfig(level=logging.DEBUG)

def test(n1,n2,n3):
    f = open(os.path.join('/Users/zhaodachuan/Downloads/test/',str(n1*n2*n3)+".txt"),"w+")
    f.write("123")
    time.sleep(1)
    f.close()
    return 

list1 = list(range(4))
if __name__ == "__main__":
    with concurrent.futures.ProcessPoolExecutor(4) as executor:
        start = time.time()
        for v in list1:
            #test(v+1,v+2,v+3)
            executor.submit(test(v+1,v+2,v+3))
        print(time.time()-start)

完成它需要4秒钟，而我预计时间是1秒钟。我应该怎么做？