> > > It appears that after a pgsql backend uses memory for sort, it doesn't
> > > get released again, at least on solaris. IE:
> >
> > That's true on many Unixen --- malloc'd space is never released back to
> > the OS until the process dies. Not much we can do about it. If you're
> > concerned, start a fresh session, or use another Unix (or at least a
> > better malloc package).
>
> Holy ugly batman...
>
> This is on solaris; is there a different/better malloc I could use?
See if there's an madvise(2) call on Slowaris, specifically, look for
something akin to (taken from FreeBSD):
MADV_FREE Gives the VM system the freedom to free pages, and tells
the system that information in the specified page range
is no longer important. This is an efficient way of
allowing malloc(3) to free pages anywhere in the address
space, while keeping the address space valid. The next
time that the page is referenced, the page might be
demand zeroed, or might contain the data that was there
before the MADV_FREE call. References made to that
address space range will not make the VM system page the
information back in from backing store until the page is
modified again.
That'll allow data that's malloc'ed to be reused by the OS. If there
is such a call, it might be prudent to stick one in the sort code just
before or after the relevant free() call. -sc
--
Sean Chittenden
