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subcmds: reduce multiprocessing serialization overhead

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Follow the same approach as 39ffd9977e to reduce serialization overhead.

Below benchmarks are tested with 2.7k projects on my workstation
(warm cache). git tracing is disabled for benchmark.

(seconds)              | v2.48 | v2.48 | this CL | this CL
	               |       |  -j32 |         |    -j32
-----------------------------------------------------------
with clean tree state:
branches (none)        |   5.6 |   5.9 |    1.0  |    0.9
status (clean)         |  21.3 |   9.4 |   19.4  |    4.7
diff (none)            |   7.6 |   7.2 |    5.7  |    2.2
prune (none)           |   5.7 |   6.1 |    1.3  |    1.2
abandon (none)         |  19.4 |  18.6 |    0.9  |    0.8
upload (none)          |  19.7 |  18.7 |    0.9  |    0.8
forall -c true         |   7.5 |   7.6 |    0.6  |    0.6
forall -c "git log -1" |  11.3 |  11.1 |    0.6  |    0.6

with branches:
start BRANCH --all     |  21.9 |  20.3 |   13.6  |    2.6
checkout BRANCH        |  29.1 |  27.8 |    1.1  |    1.0
branches (2)           |  28.0 |  28.6 |    1.5  |    1.3
abandon BRANCH         |  29.2 |  27.5 |    9.7  |    2.2

Bug: b/371638995
Change-Id: I53989a3d1e43063587b3f52f852b1c2c56b49412
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/440221
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Tested-by: Kuang-che Wu <kcwu@google.com>
Commit-Queue: Kuang-che Wu <kcwu@google.com>
This commit is contained in:
Kuang-che Wu 2024-10-22 21:04:41 +08:00 • committed by LUCI
parent 39ffd9977e
commit 8da4861b38
11 changed files with 230 additions and 174 deletions
Download patch file Download diff file Expand all files Collapse all files

27
subcmds/diff.py
View file

@ -40,7 +40,8 @@ to the Unix 'patch' command.
help="paths are relative to the repository root",
)
def _ExecuteOne(self, absolute, local, project):
@classmethod
def _ExecuteOne(cls, absolute, local, project_idx):
"""Obtains the diff for a specific project.
Args:
@ -48,12 +49,13 @@ to the Unix 'patch' command.
local: a boolean, if True, the path is relative to the local
(sub)manifest. If false, the path is relative to the outermost
manifest.
project: Project to get status of.
project_idx: Project index to get status of.
Returns:
The status of the project.
"""
buf = io.StringIO()
project = cls.get_parallel_context()["projects"][project_idx]
ret = project.PrintWorkTreeDiff(absolute, output_redir=buf, local=local)
return (ret, buf.getvalue())
@ -71,12 +73,15 @@ to the Unix 'patch' command.
ret = 1
return ret
return self.ExecuteInParallel(
opt.jobs,
functools.partial(
self._ExecuteOne, opt.absolute, opt.this_manifest_only
),
all_projects,
callback=_ProcessResults,
ordered=True,
)
with self.ParallelContext():
self.get_parallel_context()["projects"] = all_projects
return self.ExecuteInParallel(
opt.jobs,
functools.partial(
self._ExecuteOne, opt.absolute, opt.this_manifest_only
),
range(len(all_projects)),
callback=_ProcessResults,
ordered=True,
chunksize=1,
)