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Re: regression in multi-threaded git-pack-index

From
Jeff King <peff@peff.net>
Date
Mar 19, 2013, 09:59 UTC
Message-ID
<20130319095943.GA6031@sigill.intra.peff.net>
In-Reply-To
<20130319093034.GA29997@sigill.intra.peff.net>
On Tue, Mar 19, 2013 at 05:30:34AM -0400, Jeff King wrote:
Show 20 quoted lines
> On Tue, Mar 19, 2013 at 09:17:32AM +0100, Thomas Rast wrote:
> 
> > > but the line in question is:
> > >
> > >   if (deepest_delta < delta_obj->delta_depth)
> > >
> > > And in the debugger, both of those variables appear to have sane values
> > > (nor should either impacted by the patch you bisected to). On top of
> > > that, running with pack.threads=1 produces the same error. So I think it
> > > may be a false positive from valgrind, and unrelated to your issue.
> > 
> > I find that somewhat unlikely, for two reasons: memcheck is actually
> > quite good at finding uninitialized memory use, it just isn't that good
> > at distinguishing if it makes a difference.  Most false positives are of
> > the "loading an entire word and discarding most of it" kind.
> 
> Yes, that has been my experience with valgrind false positives, too. But
> if this is a real problem, it may be different from the OP's issue. It
> seems to trigger for me in v1.7.10, before Duy's threading patches. It
> does not seem to be in v1.7.5. I'm bisecting now.

Hmph. It bisects to Junio's d1a0ed1 (index-pack: show histogram when emulating "verify-pack -v", 2011-06-03), which introduces those lines. The deepest_delta variable is static, so by definition it is always initialized to something. So I guess some objects may not have delta_depth set. Still looking.

-Peff
Previous: Jeff KingNext: Jeff King
Message 6 of 46 in “regression in multi-threaded git-pack-index”
  1. Stefan ZagerMar 15, 2013
  2. Jeff KingMar 16, 2013
  3. Duy NguyenMar 16, 2013
  4. Thomas RastMar 19, 2013
  5. Jeff KingMar 19, 2013
  6. Jeff KingMar 19, 2013
  7. Jeff KingMar 19, 2013
  8. Jeff KingMar 19, 2013
  9. Thomas RastMar 19, 2013
  10. Jeff KingMar 19, 2013
  11. Thomas RastMar 19, 2013
  12. Jeff KingMar 19, 2013
  13. index-pack: always zero-initialize object_entry listJeff King, Mar 19, 2013
  14. Thomas RastMar 19, 2013
  15. Jeff KingMar 19, 2013
  16. Jeff KingMar 19, 2013
  17. index-pack: always zero-initialize object_entry listJeff King, Mar 19, 2013
  18. Thomas RastMar 19, 2013
  19. Junio C HamanoMar 19, 2013
  20. Eric SunshineMar 20, 2013
  21. Jeff KingMar 20, 2013
  22. Eric SunshineMar 20, 2013
  23. Duy NguyenMar 19, 2013
  24. index-pack: protect deepest_delta in multithread codeNguyễn Thái Ngọc Duy, Mar 19, 2013
  25. Jeff KingMar 19, 2013
  26. Thomas RastMar 19, 2013
  27. Duy NguyenMar 19, 2013
  28. index-pack: guard nr_resolved_deltas reads by lockThomas Rast, Mar 19, 2013
  29. Junio C HamanoMar 19, 2013
  30. Thomas RastMar 19, 2013
  31. Thomas RastMar 19, 2013
  32. Thomas RastMar 19, 2013
  33. Junio C HamanoMar 19, 2013
  34. sha1_file: remove recursion in packed_object_infoThomas Rast, Mar 19, 2013
  35. Junio C HamanoMar 20, 2013
  36. thomasMar 25, 2013
  37. 0/3 Recursion-free unpack_entry and packed_object_infoThomas Rast, Mar 25, 2013
  38. 1/3 sha1_file: remove recursion in packed_object_infoThomas Rast, Mar 25, 2013
  39. 2/3 Refactor parts of in_delta_base_cache/cache_or_unpack_entryThomas Rast, Mar 25, 2013
  40. Junio C HamanoMar 25, 2013
  41. thomasMar 26, 2013
  42. 3/3 sha1_file: remove recursion in unpack_entryThomas Rast, Mar 25, 2013
  43. Junio C HamanoMar 25, 2013
  44. Nicolas PitreMar 26, 2013
  45. Junio C HamanoMar 25, 2013
  46. Duy NguyenMar 20, 2013

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