Hi,

Jukka Larja (roskakori2006.delete@this.gmail.com) on January 16, 2020 10:08 am wrote:
> Brendan (btrotter.delete@this.gmail.com) on January 16, 2020 6:16 am wrote:
> > Gabriele Svelto (gabriele.svelto.delete@this.gmail.com) on January 15, 2020 5:56 am wrote:
> >
> > > That also assumes that all allocation points (including indirect
> > > ones) have proper checking. Because if they don't
> > > you'll have NULL pointers spreading through your data possibly
> > > causing a random crash at a later point where you
> > > can do absolutely nothing about it. You can't just assume that software has perfect error detection.
> >
> > Um, what?
> >
> > If there's a library function that always returns "success"
> > (but the docs don't say that success is guaranteed
> > in all future versions of the library) and another programmer calls it without checking the return value
> > (that is always "success"), then I tell the other programmer they're incompetent and refuse to work with
> > that programmer ever again (because a future version of that library might return something else).
>
> Well, that's very nice for you. Most of us can't be that picky about whose code we are dealing with.
>
> Like Linus said, you're living in a dream world.
>
> > > I'm not sure what you're talking about. The OOM killer will
> > > send you a signal which you can handle in a signal
> > > handler and you can even resume from it.
> >
> > Have you ever tried to use signals before? You get a signal while your in the middle of
> > who-knows-what; then what? Cause a deadlock while trying to acquire a lock you need to free
> > memory you were using to cache something? Inform a thread that it needs to terminate to
> > save other threads and wait for it to also receive SIGBUS and cause more problems?
>
> How exactly is it different, if the OOM is detected in some memory manager or random place calling
> malloc (or new or whatever)? No memory allocation while holding locks? Or when using some cache?
> And are you expecting that any thread can be terminated without any memory allocation?

The difference is when you find out that you need to deal with a low memory problem - in a well defined place (as soon as you try to allocate the memory) where it's easy to control the circumstances, or "at any time, almost anywhere" where you have to worry about the least convenient circumstances.

Note: If all computers had the same amount of RAM and no OS supported multi-tasking; then you wouldn't need to care much about this kind of thing. In other words; writing games for game consoles would be quite different to writing software for general purpose systems.

- Brendan