Possible memory leak when using ROOT.std.pair in a vector

[wx2017]

I’m trying the following simple code. It consume a huge amount of memory (~20 GB). The size of a vector<pair<int,float>> is 24 byte, I thus expect the total memory consumption is 24*4e5 ~10MB. Could it be a memory leak or I didn’t use the pyROOT correctly? Any helps are appreciated.

ROOT version: ROOT 6.12/07
python version: 2.7.14

import ROOT

nmax = 400000
a = ROOT.std.vector('pair<int, float>')(nmax)

for i in range(nmax):
    if i%10000 ==0:
        print(i, '\n')
    a[i] = ROOT.std.pair('int, float')(1, 2)

[eguiraud]

Hi @wx2017,
ROOT 6.12 is very old in PyROOT years. I just tried with v6.22/06, I get:

$ /usr/bin/time python repro_wx2017.py
...
3.87user 0.42system 0:04.30elapsed 99%CPU (0avgtext+0avgdata 420292maxresident)k
416inputs+40outputs (2major+44145minor)pagefaults 0swaps

Does this look more reasonable? (could you verify that the latest ROOT version does not require 20GB of RAM to execute that script?)

Cheers,
Enrico

[wx2017]

That’s indeed the case. The newer version has no issue at all. Thanks for the help!