Using up some memory with python in a controlled way

gistfile1.txt

# Eat up some memory until 30% of system total

import psutil, os
nb_process_id = os.getpid()
p = psutil.Process(nb_process_id)

from multiprocessing import Pool
import string
import random

def f(x):
    b = []
    p = psutil.Process(nb_process_id)
    letters = string.ascii_lowercase
    s=''.join(random.choice(letters) for i in range(1000))
    while True:
        memory_usage = p.memory_full_info()
        # relative memory usage
        perc = p.memory_percent()

        if len(b) % 10==0:
            #print(memory_usage)
            print("Current used memory space [rss] of the notebook process:", round(memory_usage.rss/2**30,2),'GB')
            print(perc)
        if perc < 30:
            b.append(s*x)
        else:
            print("Current used memory space [rss] of the notebook process:", round(memory_usage.rss/2**30,2),'GB')
            print(perc)
            break
    return b

_ = f(x=999999)            

# Switch mprocessing on if needed (take care of pid context)
#processes =  12
#pool = Pool(processes = processes)
#large_num=512000
#result = pool.map(f, range(large_num,large_num+8))
#pool.close()
#pool.terminate()