多进程案例复制源地址报错

一、多进程案例报错源地址不存在 问题遇到的现象和发生背景 ：
在linux系统，pycharm实现多进程复制文件

二、用代码块功能插入代码，请勿粘贴截图

import os
import multiprocessing

def copy_file(file_name,source_dir,dest_dir):
        source_path=source_dir+"/"+file_name
        dest_path=dest_dir+"/"+file_name

        with open(source_path,"rb") as source_file:
            with open(dest_path,"wb") as dest_file:
                while True:
                    data=source_file.read(1024)
                    if data:
                        dest_file.write(data)
                    else:
                        break

if __name__=="__main__":
    source_dir="/home/lila/PycharmProjects/untitled/python"

    dest_dir="/home/Desktop/test"
    #print(os.getcwd())
    #print(os.path.abspath('.'))
    try:
        os.mkdir(dest_dir)
    except:
        print("mu biao wen jian jia yi jing cun zai ")

    file_list=os.listdir(source_dir)
    print(file_list)

    for file_name in file_list:
        sub_process=multiprocessing.Process(target=copy_file,args=(file_name,source_dir,dest_dir))
        sub_process.start()

三、 运行结果及报错内容
/usr/bin/python3.5 /home/lila/PycharmProjects/untitled/hm_02_example_mutleprocess.py
mu biao wen jian jia yi jing cun zai
Traceback (most recent call last):
File "/home/lila/PycharmProjects/untitled/hm_02_example_mutleprocess.py", line 30, in
file_list=os.listdir(source_dir)
FileNotFoundError: [Errno 2] No such file or directory: './home/lila/PycharmProjects/untitled/python'