[PATCH v2 0/1] send-pack: set core.warnAmbiguousRefs=false
- Date: Tue, 06 Nov 2018 12:34:46 -0800 (PST)
- From: "Derrick Stolee via GitGitGadget" <gitgitgadget@xxxxxxxxx>
- Subject: [PATCH v2 0/1] send-pack: set core.warnAmbiguousRefs=false
I've been looking into the performance of git push for very large repos. Our
users are reporting that 60-80% of git push time is spent during the
"Enumerating objects" phase of git pack-objects.
A git push process runs several processes during its run, but one includes
git send-pack which calls git pack-objects and passes the known have/wants
into stdin using object ids. However, the default setting for
core.warnAmbiguousRefs requires git pack-objects to check for ref names
matching the ref_rev_parse_rules array in refs.c. This means that every
object is triggering at least six "file exists?" queries.
When there are a lot of refs, this can add up significantly! My PerfView
trace for a simple push measured 3 seconds spent checking these paths.
The fix is to set the global warn_on_object_refname_ambiguity to 0 for the
section that is performing these object reads.
In addition to this patch submission, we are looking into merging it into
our fork sooner .
Changes in V2: Instead of using the "-c" flag from send-pack, just set the
global. I left the name of the cover letter the same to not confuse anyone
viewing the message without threading.
Derrick Stolee (1):
pack-objects: ignore ambiguous object warnings
builtin/pack-objects.c | 6 ++++++
1 file changed, 6 insertions(+)
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-68/derrickstolee/send-pack-config-v2
Range-diff vs v1:
1: 1ef2c51550 < -: ---------- send-pack: set core.warnAmbiguousRefs=false
-: ---------- > 1: 002868ee6b pack-objects: ignore ambiguous object warnings