##// END OF EJS Templates
py3: make stdout line-buffered if connected to a TTY...
py3: make stdout line-buffered if connected to a TTY Status messages that are to be shown on the terminal should be written to the file descriptor before anything further is done, to keep the user updated. One common way to achieve this is to make stdout line-buffered if it is connected to a TTY. This is done on Python 2 (except on Windows, where libc, which the CPython 2 streams depend on, does not properly support this). Python 3 rolls it own I/O streams. On Python 3, buffered binary streams can't be set line-buffered. The previous code (added in 227ba1afcb65) incorrectly assumed that on Python 3, pycompat.stdout (sys.stdout.buffer) is already line-buffered. However the interpreter initializes it with a block-buffered stream or an unbuffered stream (when the -u option or the PYTHONUNBUFFERED environment variable is set), never with a line-buffered stream. One example where the current behavior is unacceptable is when running `hg pull https://www.mercurial-scm.org/repo/hg` on Python 3, where the line "pulling from https://www.mercurial-scm.org/repo/hg" does not appear on the terminal before the hg process blocks while waiting for the server. Various approaches to fix this problem are possible, including: 1. Weaken the contract of procutil.stdout to not give any guarantees about buffering behavior. In this case, users of procutil.stdout need to be changed to do enough flushes. In particular, 1. either ui must insert enough flushes for ui.write() and friends, or 2. ui.write() and friends get split into flushing and fully buffered methods, or 3. users of ui.write() and friends must flush explicitly. 2. Make stdout unbuffered. 3. Make stdout line-buffered. Since Python 3 does not natively support that for binary streams, we must implement it ourselves. (2.) is problematic because using unbuffered I/O changes the performance characteristics significantly compared to line-buffered (which is used on Python 2) and this would be a regression. (1.2.) and (1.3) are a substantial amount of work. It’s unclear whether the added complexity would be justified, given that raw performance doesn’t matter that much when writing to a terminal much faster than the user could read it. (1.1.) pushes complexity into the ui class instead of separating the concern of how stdout is buffered. Other users of procutil.stdout would still need to take care of the flushes. This patch implements (3.). The general performance considerations are very similar to (1.1.). The extra method invocation and method forwarding add a little more overhead if the class is used. In exchange, it doesn’t add overhead if not used. For the benchmarks, I compared the previous implementation (incorrect on Python 3), (1.1.), (3.) and (2.). The command was chosen so that the streams were configured as if they were writing to a TTY, but actually write to a pager, which is also the default: HGRCPATH=/dev/null python3 ./hg --cwd ~/vcs/mozilla-central --time --pager yes --config pager.pager='cat > /dev/null' status --all previous: time: real 7.880 secs (user 7.290+0.050 sys 0.580+0.170) time: real 7.830 secs (user 7.220+0.070 sys 0.590+0.140) time: real 7.800 secs (user 7.210+0.050 sys 0.570+0.170) (1.1.) using Yuya Nishihara’s patch: time: real 9.860 secs (user 8.670+0.350 sys 1.160+0.830) time: real 9.540 secs (user 8.430+0.370 sys 1.100+0.770) time: real 9.830 secs (user 8.630+0.370 sys 1.180+0.840) (3.) using this patch: time: real 9.580 secs (user 8.480+0.350 sys 1.090+0.770) time: real 9.670 secs (user 8.480+0.330 sys 1.170+0.860) time: real 9.640 secs (user 8.500+0.350 sys 1.130+0.810) (2.) using a previous patch by me: time: real 10.480 secs (user 8.850+0.720 sys 1.590+1.500) time: real 10.490 secs (user 8.750+0.750 sys 1.710+1.470) time: real 10.240 secs (user 8.600+0.700 sys 1.590+1.510) As expected, there’s no difference on Python 2, as exactly the same code paths are used: previous: time: real 6.950 secs (user 5.870+0.330 sys 1.070+0.770) time: real 7.040 secs (user 6.040+0.360 sys 0.980+0.750) time: real 7.070 secs (user 5.950+0.360 sys 1.100+0.760) this patch: time: real 7.010 secs (user 5.900+0.390 sys 1.070+0.730) time: real 7.000 secs (user 5.850+0.350 sys 1.120+0.760) time: real 7.000 secs (user 5.790+0.380 sys 1.170+0.710)

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pyoxidizer.bzl
98 lines | 3.3 KiB | text/x-python | PythonLexer
ROOT = CWD + "/../.."
# Code to run in Python interpreter.
RUN_CODE = "import hgdemandimport; hgdemandimport.enable(); from mercurial import dispatch; dispatch.run()"
set_build_path(ROOT + "/build/pyoxidizer")
def make_distribution():
return default_python_distribution()
def make_distribution_windows():
return default_python_distribution(flavor = "standalone_dynamic")
def make_exe(dist):
"""Builds a Rust-wrapped Mercurial binary."""
config = PythonInterpreterConfig(
raw_allocator = "system",
run_eval = RUN_CODE,
# We want to let the user load extensions from the file system
filesystem_importer = True,
# We need this to make resourceutil happy, since it looks for sys.frozen.
sys_frozen = True,
legacy_windows_stdio = True,
)
exe = dist.to_python_executable(
name = "hg",
resources_policy = "prefer-in-memory-fallback-filesystem-relative:lib",
config = config,
# Extension may depend on any Python functionality. Include all
# extensions.
extension_module_filter = "all",
)
# Add Mercurial to resources.
for resource in dist.pip_install(["--verbose", ROOT]):
# This is a bit wonky and worth explaining.
#
# Various parts of Mercurial don't yet support loading package
# resources via the ResourceReader interface. Or, not having
# file-based resources would be too inconvenient for users.
#
# So, for package resources, we package them both in the
# filesystem as well as in memory. If both are defined,
# PyOxidizer will prefer the in-memory location. So even
# if the filesystem file isn't packaged in the location
# specified here, we should never encounter an errors as the
# resource will always be available in memory.
if type(resource) == "PythonPackageResource":
exe.add_filesystem_relative_python_resource(".", resource)
exe.add_in_memory_python_resource(resource)
else:
exe.add_python_resource(resource)
# On Windows, we install extra packages for convenience.
if "windows" in BUILD_TARGET_TRIPLE:
exe.add_python_resources(
dist.pip_install(["-r", ROOT + "/contrib/packaging/requirements_win32.txt"]),
)
return exe
def make_manifest(dist, exe):
m = FileManifest()
m.add_python_resource(".", exe)
return m
def make_embedded_resources(exe):
return exe.to_embedded_resources()
register_target("distribution_posix", make_distribution)
register_target("distribution_windows", make_distribution_windows)
register_target("exe_posix", make_exe, depends = ["distribution_posix"])
register_target("exe_windows", make_exe, depends = ["distribution_windows"])
register_target(
"app_posix",
make_manifest,
depends = ["distribution_posix", "exe_posix"],
default = "windows" not in BUILD_TARGET_TRIPLE,
)
register_target(
"app_windows",
make_manifest,
depends = ["distribution_windows", "exe_windows"],
default = "windows" in BUILD_TARGET_TRIPLE,
)
resolve_targets()
# END OF COMMON USER-ADJUSTED SETTINGS.
#
# Everything below this is typically managed by PyOxidizer and doesn't need
# to be updated by people.
PYOXIDIZER_VERSION = "0.7.0"