[Development] QProcess fork() failure and overcommit

René J. V. Bertin rjvbertin at gmail.com
Tue Mar 7 14:54:29 CET 2017

Christian Kandeler wrote:

> This kind of stuff seems to happen when the parent process has allocated
> a lot of memory. I haven't debugged into it, but one idea might be that

What is a lot here? Typical usage for one of the KDevelop sessions that tends to 
be affected is around 70Mb total according to KSysGuard. Hardly a value that 
shocks me...

> the page tables themselves get to a non-trivial size and thus copying
> them causes allocation problems.

Something application-specific thus? That would fit with the observation that not 
all KDevelop sessions are always affected at the same time.

> Note also that starting a QProcess becomes enormously slow in such
> applications; for instance, on my machine here, I can only start about
> 20 processes per second from an application that has 1 GB of memory
> allocated.

As opposed to how many from a leaner application?


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