Re: Testing Program Question

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Tue, 2 Mar 2010 15:24:52 -0800 (PST)

Message-ID:

<0a9952c5-7952-4809-9ef7-a6769b877a2c@d2g2000yqa.googlegroups.com>

On Feb 17, 8:34 pm, "Leigh Johnston" <le...@i42.co.uk> wrote:

"James Kanze" <james.ka...@gmail.com> wrote in message

[...]

It is not that difficult to determine a hard limit, it will be
proportional to the size of your stack.

To determine the limit, you have to know how much stack you are
using, and how much stack is available. In general, you know
neither.

You run test cases to determine a ball park figure. Stack
size is deterministic otherwise it would be pointless to be
able to specify a stack size for a newly created thread for
example.

Stack size is not usually deterministic, at least not in a
single threaded program. In practice, stack size depends on the
current setting of ulimits, how much virtual memory is
available, and how much of that is being used by other
processes.

(Which brings up a second point: on many configurations I've
seen, the system will start thrashing and become unusable long
before you get a bad_alloc. And of course, more than a few OS's
will lie to you: operator new will return a valid pointer, but
when you try to use it, your program crashes. Or some other
program crashes.)

--
James Kanze