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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
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40
subcmds/start.py
View file

@ -21,7 +21,6 @@ from error import RepoExitError
from git_command import git
from git_config import IsImmutable
from progress import Progress
from project import Project
from repo_logging import RepoLogger
@ -29,7 +28,7 @@ logger = RepoLogger(__file__)
class ExecuteOneResult(NamedTuple):
project: Project
project_idx: int
error: Exception
@ -80,18 +79,20 @@ revision specified in the manifest.
if not git.check_ref_format("heads/%s" % nb):
self.OptionParser.error("'%s' is not a valid name" % nb)
def _ExecuteOne(self, revision, nb, project):
@classmethod
def _ExecuteOne(cls, revision, nb, default_revisionExpr, project_idx):
"""Start one project."""
# If the current revision is immutable, such as a SHA1, a tag or
# a change, then we can't push back to it. Substitute with
# dest_branch, if defined; or with manifest default revision instead.
branch_merge = ""
error = None
project = cls.get_parallel_context()["projects"][project_idx]
if IsImmutable(project.revisionExpr):
if project.dest_branch:
branch_merge = project.dest_branch
else:
branch_merge = self.manifest.default.revisionExpr
branch_merge = default_revisionExpr
try:
project.StartBranch(
@ -100,7 +101,7 @@ revision specified in the manifest.
except Exception as e:
logger.error("error: unable to checkout %s: %s", project.name, e)
error = e
return ExecuteOneResult(project, error)
return ExecuteOneResult(project_idx, error)
def Execute(self, opt, args):
nb = args[0]
@ -120,19 +121,28 @@ revision specified in the manifest.
def _ProcessResults(_pool, pm, results):
for result in results:
if result.error:
err_projects.append(result.project)
project = all_projects[result.project_idx]
err_projects.append(project)
err.append(result.error)
pm.update(msg="")
self.ExecuteInParallel(
opt.jobs,
functools.partial(self._ExecuteOne, opt.revision, nb),
all_projects,
callback=_ProcessResults,
output=Progress(
f"Starting {nb}", len(all_projects), quiet=opt.quiet
),
)
with self.ParallelContext():
self.get_parallel_context()["projects"] = all_projects
self.ExecuteInParallel(
opt.jobs,
functools.partial(
self._ExecuteOne,
opt.revision,
nb,
self.manifest.default.revisionExpr,
),
range(len(all_projects)),
callback=_ProcessResults,
output=Progress(
f"Starting {nb}", len(all_projects), quiet=opt.quiet
),
chunksize=1,
)
if err_projects:
for p in err_projects: