Profiling issue (OT)

[Colin Law]

On 13 February 2014 22:04, MR ZenWiz <mrzenwiz at gmail.com> wrote:
> This is not Ubuntu specific, but I'm not sure where to go on it.
>
> I am trying to profile a large scale Linux business application with
> gprof and I've hit a rather strange problem.
>
> The app is a backup and restore application that handles huge
> datasets.  I'm trying to track down some performance issues with it,
> but whenever the profiling version of the app runs on the full size
> dataset, it hangs at the end doing I have no idea what.  The
> non-profiling version never shows this problem.

Often this sort of problem can be due some sort of memory corruption
problem, writing off the end of an array or using an uninitialised
pointer or something similar.  It happens that the bug is benign in
the normal build but when built with profiling the effect is more
serious.  Alternatively it could be a timing issue as the timing will
change with profiling enabled.  You may consider putting some logging
in the app to work out where it is hanging.  Of course with memory
corruption the actual bug may be remote from the point in the code
where the effect is seen.  Watch out for the effect changing as you
try to diagnose it, that is indicative of corruption issues.

Colin