how to speed up multiprocessed python

Question

I'm trying to generate a Mandelbrot Set image, but the image takes ages. The code is annoyingly slow, so If you can help me speed it up, that would be very helpful. thanks. Note that code compiles and runs from my IDE. I am new to multiprocessing, so please dumb it down a bit for me.

def daemon_summoner(r):
'''allows code to be restarted with different file if crash during super high res generation'''
t = Thread(target=process_job(r))
t.start()


def process_job(r):
    """creates a slice of the set"""
    img = Image.new('1', size, color)  # B&W image
    print(int(r + 2*resolution100+1), 'of', int(resolution100 *3))
    r = r * 100
    for rval in range(100):
        for i in range(-resolution, resolution, 1):
            if abrot(((r + rval) / resolution), (i / resolution * 1j)):
                try:
                    img.putpixel((rval, i + resolution,), 0)
                except:
                    print(r, rval, i + resolution)
img.save(('z_images/' + str(resolution) + '/' + str(int(r/100)+int(resolution*.02)) + '.png'))


def abrot(x, y):
    """tests a point"""
    c = (x + y)
    z = 0 + 0j
    for _ in range(5):
        z = z * z + c
    if abs(real(z*z+c))>=2and abs(imag(z*z+c))>=2:
        return False
    for _ in range(int(resolution / 10)):
        if real(z + 0.0001) > float(real(z*z+c)) > real(z - 0.0001):
            return True
        z = z * z + c
        if abs(real(z)) >= 2:
            return False
    return True

Answer 1

Mandelbrot迭代z * z + c可能需要数十亿次操作才能生成单个图像，因此加快速度的第一步是删除iterate_once函数并在线完成工作。