Add guppy backend

[dxe4]

related to my comment here #236 (comment)
with implementation of guppy3 we can get the right values.

note this implementation does self.prevlines[-1] == self.prev_lineno: for guppy backend only, because repeating [i for i in range(0, 10000000)] makes the guppy backend extremely slow. although this may not be ideal or acceptable i thought it's worth sharing the code.

 @profile def myfn_py(): ones = [1] * NBR_ITEMS twos = [i + 1 for i in ones] return twos @profile def myfn_np(): ones_np = np.ones(NBR_ITEMS) twos_np = ones_np+1 return twos_np myfn_np() myfn_py() python -m memory_profiler --backend guppy prof.py Line # Mem usage Increment Line Contents ================================================ 11 14.191 MiB 14.191 MiB @profile 12 def myfn_py(): 13 18.006 MiB 3.815 MiB ones = [1] * NBR_ITEMS 14 22.098 MiB 4.091 MiB twos = [i + 1 for i in ones] 15 return twos Filename: prof.py Line # Mem usage Increment Line Contents ================================================ 18 14.189 MiB 14.189 MiB @profile 19 def myfn_np(): 20 18.005 MiB 3.817 MiB ones_np = np.ones(NBR_ITEMS) 21 21.820 MiB 3.815 MiB twos_np = ones_np+1 22 21.820 MiB 0.000 MiB return twos_np 

[dxe4]

this can cause issues if you want to measure the memory of a side effect eg

[foo() for i in range(0, 500)] def foo(): make_big_array = [i for i in random.randint(0, int(1e9))] 

i haven't tested it.
although it will give correct results for this case #236 (comment)