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Re: Git push performance problems with ~100K refs

From
Junio C Hamano <gitster@pobox.com>
Date
Mar 30, 2012, 02:12 UTC
Message-ID
<7v7gy2q1kq.fsf@alter.siamese.dyndns.org>
In-Reply-To
<201203291818.49933.mfick@codeaurora.org>
Martin Fick <mfick@codeaurora.org> writes:
Show 6 quoted lines
> Does anyone have any hints as to what might be wrong with 
> the receiving end algorithm that would cause a small change 
> to use so much CPU?  Is there anything that can be done 
> about it?  I noticed that the --all option will effectively 
> feed all the 100K refs to rev-list, is this really 
> necessary?

It is trying to minimize the transfer cost. By showing a ref to the sending side, you prove you have chains of commits leading to that commit and the sender knows that it does not have to send objects that are reachable from that ref. One thing you could immediately do is de-dup the 100k refs but we may already do that in the current code.

> Are there any tests that I can perform to help 
> debug this?

You do not need to "help debug" it. It's cause is already known: the receiver exposes too many refs to the sending side.

We've talked about possible solutions but no concrete design nor code is there yet.

Previous: Martin FickNext: Martin Fick
Message 2 of 37 in “Git push performance problems with ~100K refs”
  1. Martin FickMar 30, 2012
  2. Junio C HamanoMar 30, 2012
  3. Martin FickMar 30, 2012
  4. Jeff KingMar 30, 2012
  5. Jeff KingMar 30, 2012
  6. Martin FickMar 30, 2012
  7. 1/3 add mergesort() for linked listsRené Scharfe, Mar 31, 2012
  8. Junio C HamanoApr 5, 2012
  9. René ScharfeApr 8, 2012
  10. Junio C HamanoApr 9, 2012
  11. Stephen BoydApr 11, 2012
  12. Junio C HamanoApr 11, 2012
  13. 2/3 commit: use mergesort() in commit_list_sort_by_date()René Scharfe, Mar 31, 2012
  14. 3/3 revision: insert unsorted, then sort in prepare_revision_walk()René Scharfe, Mar 31, 2012
  15. Martin FickMar 31, 2012
  16. Junio C HamanoMar 31, 2012
  17. Martin FickApr 2, 2012
  18. Shawn PearceApr 2, 2012
  19. Martin FickApr 2, 2012
  20. Shawn PearceApr 2, 2012
  21. Jeff KingApr 2, 2012
  22. Jeff KingApr 2, 2012
  23. Martin FickApr 2, 2012
  24. Nguyen Thai Ngoc DuyApr 3, 2012
  25. Martin FickApr 3, 2012
  26. 0/3 Commit cacheNguyễn Thái Ngọc Duy, Apr 3, 2012
  27. 1/3 parse_commit_buffer: rename a confusing variable nameNguyễn Thái Ngọc Duy, Apr 3, 2012
  28. 2/3 Add commit cache to help speed up commit traversalNguyễn Thái Ngọc Duy, Apr 3, 2012
  29. 3/3 Add parse_commit_for_rev() to take advantage of sha1-cacheNguyễn Thái Ngọc Duy, Apr 3, 2012
  30. Nguyen Thai Ngoc DuyApr 5, 2012
  31. Shawn PearceApr 6, 2012
  32. Nguyen Thai Ngoc DuyApr 7, 2012
  33. Nguyen Thai Ngoc DuyApr 3, 2012
  34. Jeff KingApr 2, 2012
  35. René ScharfeApr 2, 2012
  36. Jeff KingApr 3, 2012
  37. Jeff KingApr 3, 2012

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