I spent some time last week running git through the paces with
valgrind's memcheck tool. The good news is that I didn't find any
serious issues, so we are doing a pretty good job overall. The bad news
is that running the whole test suite with valgrind takes a few hours on
a quad-core (but thank goodness for "make -j4 test").
I did uncover a few potential problems, and patches are in the latter
part of the series. I suppose an argument could be made that these fixes
are code churn, since these are not problems in practice, but I think
they are worth fixing. The fixes are few in number and small, and we are
very close to a valgrind-error-free code-base, which would make it easy
to spot any new problems when they arise. We could always suppress these
errors, but there is the possibility of an overzealous suppression
masking a real problem (especially if one of these issues changes from
theoretical to practical).
There are a few things I don't like:
1. The "fake git PATH" is set up by the Makefile, since it needs to
know which dashed commands to override (based on $(PROGRAMS)).
I think it would be nicer if the test script itself set this up when
--memcheck was requested, so that we always know it is fresh. But:
- if the fake PATH isn't inside the trash directory, then we have
a problem with multiple tests trying to set it up at the same
time
- if the fake PATH is inside the trash directory, I'm not sure of
the best place to put it, as I don't want to influence the
outcome of the tests. It could go into .git/valgrind, without
hurting anything.
2. I wanted to have a completely clean valgrind run before posting.
With these patches, the only errors I get are for an uninitialized
"struct stat" in t4121 and t4127. After much looking (including
carefully reading the code, and using a a debugger, which shows the
data in question looking very much initialized) I can't figure out
what the problem might be. So it might simply be a false positive in
valgrind, but I would like another set of eyes.
-Peff
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