Re: [PATCH] stack: Add new '-n MAXFRAMES' option. Resolve addresses after unwind.

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Mon, 06 Jan 2014 15:52:08 +0100, Mark Wielaard wrote:
> The default output should be useful as is.

Which it is not.  As for the common case of stack overflow by infinite loop it
does not show the reason.


> Of course they can tweak if however they want.
> eu-stack has many options to tailor the output to your need.

The problem is that:

 * One should not need to tweak a program to perform its primary functionality.

 * It leads to bugs as in 95% of cases it does what one expects so external
   tools will forget passing -n 0 to it, breaking only later on more
   complicated input data.


> But by default it provides [n=2048] frames for all threads of a process.
> A bit too much for my liking,

It is too much to print on a console anyway while it is still breaking the
stack overflow crashes.  It is had only two cons, no pro.


> But I do think even without a tty one should be explicit
> about what one wants.

One is explicit already by calling eu-stack.  Command "eu-stack" does not
suggest me it is in fact "eu-bottom-of-stack".


> > Paging, a-la git,
[...]
> > applying a default limit only when stdin is a tty would still be better, IMO.
> 
> I think that is a little too fancy, but yeah, that could have been
> another choice. But I do think even without a tty one should be explicit

These are all valid choices.  And not breaking the primary functionality of
eu-stack.


> BTW. What does seem useful is a new (default) option --tail, that would
> only show the last n frames of each thread's backtrace.

For tail there is /usr/bin/tail:
	https://en.wikipedia.org/wiki/Unix_philosophy#McIlroy:_A_Quarter_Century_of_Unix
	Write programs that do one thing and do it well. Write programs to
	work together. Write programs to handle text streams, because that is
	a universal interface.

The same way there is /usr/bin/head or /usr/bin/less.


> If detection of infinite backtraces can be done reliably.

It is always reliable.


Jan