Linus' recent patch to invoke limiting on rename detection broke my
ability to use cherry-picking on one project. This project has about
4300 files on one branch (a), 2500 on a later branch (b), 226 commits in
total between the two branches, and a convoluted history of how branch a
morphed into branch b. About 50 files were renamed in the transition,
and we need to migrate patches from the still maintained branch a onto
the new branch b.
Prior to Linus' recent patch to limit rename detection (0024a549),
cherry picking a patch from a to b, where the patch affected just one
file, often took about 45 seconds on a 3 GHz pentium 4 with the CPU
pegged at 100% for the duration. The cherry picking always succeeded and
correctly followed renames, but was very slow.
Following Linus' patch, the cherry picking fails with a merge conflict
(almost instantly), complaining the file has been deleted on b but
modified on a, i.e., the rename detection does not work. I tried raising
diff.renameLimit to 100000, that seems to have no effect whatsoever on
cherry-pick (the process aborts with a conflict almost immediately).
Curiously, using "git format-patch x..y --stdout | git am -3" succeeds
in this case, and runs in well less than a second. This performance
seems unchanged by the rename detection limit patch.
So, the rename limit patch "broke" git for this usage, though one could
reasonably argue the previous code was so slow as to be broken anyway.
The curious thing to me is the vast superiority of whatever
git-format-patch|git-am -3 does, and I wonder if that isn't a
fundementally better design for cherry picking than git-cherry-pick
implements (it obviously is for this case).
Mark
-
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
