| Message ID | 20181012135218.14439-1-rstrain@swri.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | subtree: performance improvement for finding unexpected parent commits | expand |
Original failed to include the note that this patch is for the 'next' branch, my apologies. > -----Original Message----- > From: Roger Strain <rstrain@swri.org> > Sent: Friday, October 12, 2018 8:52 AM > To: git@vger.kernel.org > Cc: Strain, Roger L. <roger.strain@swri.org> > Subject: [PATCH] subtree: performance improvement for finding > unexpected parent commits > > After testing a previous patch at larger scale, a performance issue was > detected when using git show to locate parent revisions, with a single run of > the git show command taking 2 seconds or longer in a complex repo. > When the command is required tens or hundreds of times in a run of the > script, the additional wait time is unaccepatable. Replacing the command > with git rev-parse resulted in significantly increased performance, with the > command in question returning instantly. > > Signed-off-by: Roger Strain <rstrain@swri.org> > Thanks-to: Junio C Hamano <gitster@pobox.com> > --- > contrib/subtree/git-subtree.sh | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh > index 1c157dbd9..147201dc6 100755 > --- a/contrib/subtree/git-subtree.sh > +++ b/contrib/subtree/git-subtree.sh > @@ -633,7 +633,7 @@ process_split_commit () { > else > # processing commit without normal parent information; > # fetch from repo > - parents=$(git show -s --pretty=%P "$rev") > + parents=$(git rev-parse "$rev^@") > extracount=$(($extracount + 1)) > fi > > -- > 2.19.1
Roger Strain <rstrain@swri.org> writes: > After testing a previous patch at larger scale, a performance issue was > detected when using git show to locate parent revisions, with a single > run of the git show command taking 2 seconds or longer in a complex repo. > When the command is required tens or hundreds of times in a run of the > script, the additional wait time is unaccepatable. Replacing the command > with git rev-parse resulted in significantly increased performance, with > the command in question returning instantly. > > Signed-off-by: Roger Strain <rstrain@swri.org> > Thanks-to: Junio C Hamano <gitster@pobox.com> That usually is spelled as "Helped-by:". Will queue. Thanks. I still find it disturbing not to know why "show -s --format=..." takes measurable time, though. "-s" means "we do not need any diff output", so it ought to be comparable to "git cat-file commit $rev" with some formatting, but apparently your repository is making Git spend a lot more than that. Puzzled... > --- > contrib/subtree/git-subtree.sh | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh > index 1c157dbd9..147201dc6 100755 > --- a/contrib/subtree/git-subtree.sh > +++ b/contrib/subtree/git-subtree.sh > @@ -633,7 +633,7 @@ process_split_commit () { > else > # processing commit without normal parent information; > # fetch from repo > - parents=$(git show -s --pretty=%P "$rev") > + parents=$(git rev-parse "$rev^@") > extracount=$(($extracount + 1)) > fi
diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh index 1c157dbd9..147201dc6 100755 --- a/contrib/subtree/git-subtree.sh +++ b/contrib/subtree/git-subtree.sh @@ -633,7 +633,7 @@ process_split_commit () { else # processing commit without normal parent information; # fetch from repo - parents=$(git show -s --pretty=%P "$rev") + parents=$(git rev-parse "$rev^@") extracount=$(($extracount + 1)) fi
After testing a previous patch at larger scale, a performance issue was detected when using git show to locate parent revisions, with a single run of the git show command taking 2 seconds or longer in a complex repo. When the command is required tens or hundreds of times in a run of the script, the additional wait time is unaccepatable. Replacing the command with git rev-parse resulted in significantly increased performance, with the command in question returning instantly. Signed-off-by: Roger Strain <rstrain@swri.org> Thanks-to: Junio C Hamano <gitster@pobox.com> --- contrib/subtree/git-subtree.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)