Can this be modified to run faster? - performance

Question

I'm creating a word list using python that hits every combination of of characters which is a monster of a calculation past 944. Before you ask where I'm getting 94, 94 covers ASCII characters 32 to 127. Understandably this function runs super slow, I'm curious if there's a way to make it more efficient.
This is the meat and potatoes of the my code.
def CreateTable(name,ASCIIList,size):
f = open(name + '.txt','w')
combo = itertools.product(ASCIIList, repeat = size)
for x in combo:
passwords = ''.join(x)
f.write(str(passwords) + '\n')
f.close()
I'm using this so that I can make lists to use in a brute force where I don't know the length of the passwords or what characters the password contains. Using a list like this I hit every possible combination of words so I'm sure to hit the right one eventually. Having stated earlier that this is a slow program this also slow to read in and will not my first choice for a brute force, this more or less for a last ditch effort.
To give you an idea of how long that piece of code runs. I was creating all the combinations of size 5 and ran for 3 hours ending at a little over 50GB.

Answer 1

Warning : I have not tested this code.
I would convert combo to a list: combo_list = list(combo)
I would then break it into chunks:
# https://stackoverflow.com/a/312464/596841
def get_chunks(l, n):
"""Yield successive n-sized chunks from l."""
for i in range(0, len(l), n):
yield l[i:i + n]
# Change 1000 to whatever works.
chunks = get_chunks(combo_list, 1000)
Next, I would use multithreading to process each chunk:
class myThread (threading.Thread):
def __init__(self, chunk_id, chunk):
threading.Thread.__init__(self)
self.chunk_id = chunk_id
self.chunk = chunk
def run(self):
print ("Starting " + self.chunk_id)
process_data(self.chunk)
print ("Exiting " + self.chunk_id)
def process_data():
f = open(self.chunk_id + '.txt','w')
for item in self.chunk:
passwords = ''.join(item)
f.write(str(passwords) + '\n')
f.close()
I would then do something like this:
threads = []
for i, chunk in enumerate(chunks):
thread = myThread(i, chunk)
thread.start()
threads.append(thread)
# Wait for all threads to complete
for t in threads:
t.join()
You could then write another script to merge all the output files, if you need.

Answer 2

I did some testing on this, and I think the main problem is that you're writing in text mode.
Binary mode is faster, and you're only dealing with ASCII, so you might as well just spit out bytes rather than strings.
Here's my code:
import itertools
import time
def CreateTable(name,ASCIIList,size):
f = open(name + '.txt','w')
combo = itertools.product(ASCIIList, repeat = size)
for x in combo:
passwords = ''.join(x)
f.write(str(passwords) + '\n')
f.close()
def CreateTableBinary(name,ASCIIList,size):
f = open(name + '.txt', 'wb')
combo = itertools.product(ASCIIList, repeat = size)
for x in combo:
passwords = bytes(x)
f.write(passwords)
f.write(b'\n')
f.close()
def CreateTableBinaryFast(name,first,last,size):
f = open(name + '.txt', 'wb')
x = bytearray(chr(first) * size, 'ASCII')
while True:
f.write(x)
f.write(b'\n')
i = size - 1
while (x[i] == last) and (i > 0):
x[i] = first
i -= 1
if i == 0 and x[i] == last:
break
x[i] += 1
f.close()
def CreateTableTheoreticalMax(name,ASCIIList,size):
f = open(name + '.txt', 'wb')
combo = range(0, len(ASCIIList)**size)
passwords = b'A' * size
for x in combo:
f.write(passwords)
f.write(b'\n')
f.close()
print("writing real file in text mode")
start = time.time()
chars = [chr(x) for x in range(32, 126)]
CreateTable("c:/temp/output", chars, 4)
print("that took ", time.time() - start, "seconds.")
print("writing real file in binary mode")
start = time.time()
chars = bytes(range(32, 126))
CreateTableBinary("c:/temp/output", chars, 4)
print("that took ", time.time() - start, "seconds.")
print("writing real file in fast binary mode")
start = time.time()
CreateTableBinaryFast("c:/temp/output", 32, 125, size)
print("that took ", time.time() - start, "seconds.")
print("writing fake file at max speed")
start = time.time()
chars = [chr(x) for x in range(32, 126)]
CreateTableTheoreticalMax("c:/temp/output", chars, 4)
print("that took ", time.time() - start, "seconds.")
Output:
writing real file in text mode
that took 101.5869083404541 seconds.
writing real file in binary mode
that took 40.960529804229736 seconds.
writing real file in fast binary mode
that took 35.54869604110718 seconds.
writing fake file at max speed
that took 26.43029284477234 seconds.
So you can see a pretty big improvement just by switching to binary mode.
Also, there still seems to be some slack to take up, since omitting the itertools.product and writing hard-coded bytes is even faster. Maybe you could write your own version of product that directly output bytes-like objects. Not sure about that.
Edit: I had a go at a manual itertools.product working directly on a bytearray. It's a bit faster - see "fast binary mode" in the code.