When using multiprocessing, something goes wrong.

[dotcom]

In the evaluation, I tried to output the evaluation value and the individual at that time.

def func(x,y,z,w):
    return x*y + z + 4*w

train = []
for i in range(DATASIZE):
    X = []
    for j in range(4):
        X.append(random.uniform(10,100))
    X.append(random.choice([func(X[0],X[1],X[2],X[3]),0,0,0,0]))
    train.append(X)


def step_function(x):
  if x>0:
    return 1
  else:
    return 0

def sigmoid(x):
  return 1 / (1+np.exp(-x))

def mapnp(f,x):
    return np.array(list(map(f,x)))

def paramfunc(vec, mat1, mat2, mat3):
    return mapnp(step_function, np.dot(mapnp(sigmoid,np.dot(mapnp(sigmoid, np.dot(vec, mat1)), mat2)), mat3))

def listparamfunc(vec, paramlist):
    mat1 = [paramlist[0:4], paramlist[4:8], paramlist[8:12], paramlist[12:16]]
    mat2 = [paramlist[16:20], paramlist[20:24], paramlist[24:28], paramlist[28:32]]
    mat3 = paramlist[32:]
    return paramfunc(np.array(vec), np.array(mat1), np.array(mat2), np.array(mat3))

def evalind(individual):
    profit = 0
    nptrain = np.array(train)
    result = listparamfunc(nptrain[:,0:4],individual)
    for x in range(len(train)):
        if result[x] == 1:
            profit = profit + train[x][4] - 1000
    ################################################
    print(profit, individual) ############ output ############
    ################################################
    return profit,


creator.create("FitnessMax", base.Fitness, weights=(1.0,))
creator.create("Individual", list, fitness=creator.FitnessMax)

toolbox = base.Toolbox()
toolbox.register("attr_float", random.uniform, -1, 1)
toolbox.register("individual", tools.initRepeat, creator.Individual, toolbox.attr_float, 36)
toolbox.register("population", tools.initRepeat, list, toolbox.individual)

toolbox.register("evaluate", evalind)
toolbox.register("mate", tools.cxUniform, indpb=MATE_GENOM_RATE)
toolbox.register("mutate", tools.mutGaussian, indpb=MUTATE_GENOM_RATE, mu=MUTATE_MU, sigma=MUTATE_SIGMA)
toolbox.register("select", tools.selTournament, tournsize=TOURNAMENT)



def main(pop, gen=GEN):
    random.seed(time.time())
    if pop == None:
        pop = toolbox.population(n=500)
    hof = tools.HallOfFame(1)

    pop, log = algorithms.eaSimple(pop, toolbox, MATE_RATE, MUTATE_RATE, gen,halloffame=hof, verbose=True)
    return pop, log, hof




if __name__ == "__main__":

    pool = multiprocessing.Pool(11)
    toolbox.register("map", pool.map)

    pop, log, hof = main(pop=None, gen=10)

    best = tools.selBest(pop, 1)[0]
    print("best: ", best)
    print("best.fitness.values : ", best.fitness.values)
    print("evalind(best) : ", evalind(best))

This was the one with the highest rating.

531564.2498946949 : [-0.014781777922400874, -0.3787021885147608, ....

However, when I evaluated best (hof) again after completion, different value ​​cames out. (The gene is the same)

best:  [-0.014781777922400874, -0.3787021885147608, ....
best.fitness.values :  (531564.2498946949,)

evalind(best) :  (265238.98228751967,)  #     !=531564.2498946949

turn off multiprocessing

Several studies have shown that multiprocessing is affecting me.
As a result, when I stopped multiprocessing, this was output correctly.

#pool = multiprocessing.Pool(11)
#toolbox.register("map", pool.map)

best.fitness.values :  (511370.0290722571,)
evalind(best) :  (511370.0290722571,)

why?
Thank you.

[fmder]

Your evaluation function depends on a global variable train that is randomly generated. This cannot work in multiprocessing as each process will have a different train object.

[dotcom]

Are different objects but different values?

[dotcom]

It is randomly generated only once.

[dotcom]

Its really...

pid, and data

17576  :  [[56.37660726530297, 57.21448899086297, ...
14992  :  [[10.732069581858903, 27.533883587933413,...

[fmder]

Are you on Windows or Unix? On Windows It should be generated twice

[dotcom]

It is Windows.
When I tried it on Ubuntu now, there was no problem.
wow why?
What kind of mechanism is it? If you know, please tell me briefly.
Isn't Copy on write in windows?

[fmder]

Unix fork the process and copy the memory. Windows starts k processes, thus the script is entirely run in each process. You can find more information in the multiprocessing module documentation. Le sam. 18 mai 2019 09 h 15, dotcom <notifications@github.com> a écrit :

…

It is Windows. When I tried it on Ubuntu now, there was no problem. wow why? What kind of mechanism is it? If you know, please tell me briefly. Isn't Copy on write in windows? — You are receiving this because you modified the open/close state. Reply to this email directly, view it on GitHub <#355?email_source=notifications&email_token=AAHKXQSVC6KNOBH7VUPXXS3PV76PVA5CNFSM4HN2HBE2YY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGODVWOOZY#issuecomment-493676391>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAHKXQTLJTT7BBPIWXPZJODPV76PVANCNFSM4HN2HBEQ> .

[dotcom]

Thank you for your kindness.