Re: Issue 1475 in lilypond: crash with many markups between scores

[Joe Neeman]

On Thu, Jan 20, 2011 at 7:46 PM, David Kastrup <address@hidden> wrote:

> address@hidden writes:
>
> > By the way, the excessive memory usage was in
> > Page_breaking::line_divisions_rec. This function theoretically uses
> > memory which is exponential in the number of systems, but it should
> > never be an issue because of the way the function is used; the
> > lower_bound and upper_bound arguments keep memory usage down to
> > something linear in the number of systems. The problem was that I
> > changed the way that systems were counted internally in the page
> > breaker (before, system_count() counted systems, titles and markups,
> > but I changed it to only count systems). But I didn't make the change
> > in all of the places where it was required, so the system_count
> > argument to line_divisions_rec got out of sync with the lower_bound
> > and upper_bound arguments, causing exponential memory usage (but only
> > when there are enough titles and markups to make things sufficiently
> > out of sync).
>
> I have not looked at the code, but this sounds like an accident waiting
> to happen again and/or like being hard to read.  Would there be a
> feasible way to reduce the place where the actual updating is being done
> to _one_ location (like an inline private member function or whatever
> else) instead of needing to cater with continuing having to do maintain
> any further "change in all of the places where it was required"?
>

There used to be two functions to compute system_count. Now there is only
one.

Joe