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Fixes issue #19506: Use a memoryview to avoid a data copy when piping data

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to stdin within subprocess.Popen.communicate.  5-10% less cpu usage.
This commit is contained in:
Gregory P. Smith 2013-12-07 19:12:46 -08:00
parent 6c527cf37f
commit 774f909489
2 changed files with 8 additions and 2 deletions
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5
Lib/subprocess.py
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@ -1621,6 +1621,9 @@ class Popen(object):
self._save_input(input) self._save_input(input)
if self._input:
input_view = memoryview(self._input)
while self._fd2file: while self._fd2file:
timeout = self._remaining_time(endtime) timeout = self._remaining_time(endtime)
if timeout is not None and timeout < 0: if timeout is not None and timeout < 0:
@ -1638,7 +1641,7 @@ class Popen(object):
for fd, mode in ready: for fd, mode in ready:
if mode & select.POLLOUT: if mode & select.POLLOUT:
chunk = self._input[self._input_offset : chunk = input_view[self._input_offset :
self._input_offset + _PIPE_BUF] self._input_offset + _PIPE_BUF]
try: try:
self._input_offset += os.write(fd, chunk) self._input_offset += os.write(fd, chunk)

3
Misc/NEWS
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@ -18,6 +18,9 @@ Core and Builtins
Library Library
------- -------
- Issue #19506: Use a memoryview to avoid a data copy when piping data
to stdin within subprocess.Popen.communicate. 5-10% less cpu usage.
- Issue #19839: Fix regression in bz2 module's handling of non-bzip2 data at - Issue #19839: Fix regression in bz2 module's handling of non-bzip2 data at
EOF, and analogous bug in lzma module. EOF, and analogous bug in lzma module.