[Python-checkins] cpython (merge 3.3 -> default): Fixes issue #19929: Call os.read with 32768 within subprocess.Popen
gregory.p.smith
python-checkins at python.org
Sun Dec 8 19:58:41 CET 2013
http://hg.python.org/cpython/rev/4de4b5a4e405
changeset: 87839:4de4b5a4e405
parent: 87837:0f587fe304be
parent: 87838:03a056c3b88e
user: Gregory P. Smith <greg at krypto.org>
date: Sun Dec 08 10:58:28 2013 -0800
summary:
Fixes issue #19929: Call os.read with 32768 within subprocess.Popen
communicate rather than 4096 for efficiency. A microbenchmark shows
Linux and OS X both using ~50% less cpu time this way.
files:
Lib/subprocess.py | 2 +-
Misc/NEWS | 4 ++++
2 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/Lib/subprocess.py b/Lib/subprocess.py
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1601,7 +1601,7 @@
selector.unregister(key.fileobj)
key.fileobj.close()
elif key.fileobj in (self.stdout, self.stderr):
- data = os.read(key.fd, 4096)
+ data = os.read(key.fd, 32768)
if not data:
selector.unregister(key.fileobj)
key.fileobj.close()
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -24,6 +24,10 @@
- Issue #19343: Expose FreeBSD-specific APIs in resource module. Original
patch by Koobs.
+- Issue #19929: Call os.read with 32768 within subprocess.Popen.communicate
+ rather than 4096 for efficiency. A microbenchmark shows Linux and OS X
+ both using ~50% less cpu time this way.
+
- Issue #19506: Use a memoryview to avoid a data copy when piping data
to stdin within subprocess.Popen.communicate. 5-10% less cpu usage.
--
Repository URL: http://hg.python.org/cpython
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