[Interest] QProcess performance issues

[René J.V. Bertin]

On Wednesday May 13 2015 06:49:18 Thiago Macieira wrote:
> On Tuesday 12 May 2015 17:36:59 Matthew Woehlke wrote:
> > After further testing, it seems that the problem is caused by writing to
> > the process's stdin? Is there some issue with writing to a QProcess's
> > input pipe on Windows? (We are writing quite a lot - many MiB's - of
> > data...)
> 
> Yes. The QWindowsPipeWriter is a horrible hack to a horrible Win32 API.
> 
> I think Friedemann was implementing some optimisations there for 5.5, but as 
> long as you use Windows, you're going to have poor pipe performance.

FWIW, I did something similar a couple of years back. I didn't use Qt, but good old popen(). I did modify the Win32 version that (IIRC) ships/ped with MSVC (I used the Express version) so that it didn't open a console window and could be fine-tuned.
Look for popenEx() in https://github.com/RJVB/brigade-helpers .

I never noticed particular performance issues with the input this code was used with (2-4Gb max).

HTH,
R.