Python 2.x (not) list comprehension with multithreading

not_list_comprehension_with_multithreading.py

import multiprocessing
import itertools

def get_trajectory(arg1, arg1):
  return [999,888,777,666]

def get_traj_as_star(arg):
    return get_trajectory(arg[1], arg[2])

def run_multi_particle(num_particle, num_time, num_mesh, multi_thread=True):
    if not multi_thread:
        return [get_trajectory(num_time, num_mesh) for _ in range(num_particle)]  
    
    # get [get_trajectory(num_time, num_mesh) for _ in range(num_particle)] with multithreading way!
    cpus = 7
    pool = multiprocessing.Pool(processes=cpus)
    ret =  pool.map(get_traj_as_star, itertools.izip(range(num_particle), itertools.repeat(num_time), itertools.repeat(num_mesh)))
    pool.terminate() # mandatory
    return ret