On 7/26/15 10:35 AM, Johan Holmberg via Digitalmars-d wrote:
On Sat, Jul 25, 2015 at 10:12 PM, Andrei Alexandrescu via Digitalmars-d <digitalmars-d@puremagic.com <mailto:digitalmars-d@puremagic.com>> wrote: On 7/25/15 1:53 PM, Johan Holmberg via Digitalmars-d wrote: Thanks, my question seems like a carbon copy of the Stack Overflow article :) Somehow I had missed it when googling. I download a dmd 2.068 beta, and re-tried with my input file: now the D program takes 1.6s (a 10x improvement). Great, though it still seems to be behind the C++ version, which is a bummer. -- Andrei My C++ program was actually doing C-style IO via <stdio.h>. I didn't think about the distinction C/C++ when reporting the earlier numbers. If I switch to full C++ style: <fstream> + <string> + C++ version of getline(), then the C++-solution is even slower than Python: 5.2s. I think it is the C++ libraries of Clang on MacOS Yosemite that are slow. This prompted me to re-run the tests on a Linux machine (Ubuntu 14.04), still with the same input file, a text file with 7M lines and total size of 466MB: C++ with <stdio.h> style IO: 0.40s C++ with <fstream> style IO: 0.31s D 2.067 1.75s D 2.068 beta 2: 0.69s Perl: 1.49s Python: 1.86s So on Ubuntu, the C++ <fstream> version was clearly best. And the improvement in DMD 2.068 beta "only" a factor of 2.5 from 2.067. /johan
I think we should investigate this and bring performance to par. Anyone interested? -- Andrei
