Re: [Valgrind-users] at a loss

[Nicholas N. <nj...@ca...>]

On Tue, 13 May 2003, Michael Labhard wrote:

> I am at a loss as to how to use valgrind.  I have read the manual and a
> howto.  Using this command
>
> export GLIBCPP_FORCE_NEW=1;
> valgrind
> --skin=memcheck

Memcheck is the default skin, so this flag is unnecessary

> --leak-check=yes
> --show-reachable=yes

Don't use --show-reachable=yes and you won't the the "still reachable in
loss record" messages below;  they're not so important, they show memory
that your program could have freed (it's still reachable via some
pointer) but didn't bother to.

> --logfile=debug.out
> --suppressions=xfree-3.supp
> --suppressions=xfree-4.supp --suppressions=default.supp --suppressions=glibc-2.2.supp

default.supp is used as the default suppression file so you don't need to
specify it.  It's constructed at ./configure time from the relevant
xfree/glibc/linux .supp files, so you don't need to mentiont them either.

> src/.libs/lt-myapp
>
> My application produces hundreds of lines looking like
>
> ==26316== 216 bytes in 21 blocks are still reachable in loss record 77 of 124
> ==26316==    at 0x40160989: malloc (in /usr/lib/valgrind/valgrind.so)
> ==26316==    by 0x40B33B2F: __GI___strdup (in /lib/libc-2.3.1.so)
> ==26316==    by 0x40F5C37A: resolve_object (in /usr/X11R6/lib/libX11.so.6.2)
> ==26316==    by 0x40F5BF7C: _XlcDynamicLoad (in /usr/X11R6/lib/libX11.so.6.2)
> ==26316==
>
> What do I do with this stuff?  It looks like it comes from an X11 library but
> the command line includes suppressions for X11.  Why isn't X11 output
> suppressed?  Where do I get a suppressions file for Qt?

If you look in any of the .supp files, you'll see many suppressions for
individual errors.  These have been added as they were encountered.  They
should cover most X11 errors people get, but we may have missed some, or
your machine might have an unusual configuration that means some errors
are getting through.  You can write your own suppressions;  the manual
currently doesn't explain how to very well, it would be easier to check
out the CVS HEAD (from sourceforge.net) and use the --gen-suppressions
feature to automatically generate suppressions (the feature isn't in
1.9.6).

But first, just try "valgrind --leak-check=yes <program>", see how that
works.

N