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GeezerVison is showing github.com — gh-129005: _pyio.BufferedIO remove copy on readall by cmaloney · Pull Request #129454 · python/cpython

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@cmaloney

@cmaloney cmaloney commented Jan 29, 2025 •
edited by bedevere-app Bot
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Slicing buf and appending chunk would always result in a copy / another memory allocation of the length of chunk. Commonly in a readall there is no already read data in buf, and the amount of data read may be large, so the copy is expensive.

  • Issue: Reduce copies when reading files in pyio, match behavior of _io #129005

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@cmaloney
pythongh-129005: _pyio.BufferedIO remove copy on readall
7e0f7ae 
Slicing buf and appending chunk would always result in a copy. Commonly
in a readall there is no already read data in buf, and the amount of
data read may be large, so the copy is expensive.
@bedevere-app bedevere-app Bot added the awaiting review label Jan 29, 2025
@bedevere-app bedevere-app Bot mentioned this pull request Jan 29, 2025
Reduce copies when reading files in pyio, match behavior of _io #129005
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vstinner
vstinner reviewed Jan 30, 2025
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Comment thread Misc/NEWS.d/next/Library/2025-01-29-00-00-01.gh-issue-129005.aV_3O8.rst Resolved

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@vstinner
Update Misc/NEWS.d/next/Library/2025-01-29-00-00-01.gh-issue-129005.a…
fe251e8 
…V_3O8.rst
vstinner
vstinner approved these changes Jan 30, 2025
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LGTM

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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting review labels Jan 30, 2025
@vstinner
vstinner enabled auto-merge (squash) January 30, 2025 10:55
vstinner
vstinner reviewed Jan 30, 2025
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Comment thread Misc/NEWS.d/next/Library/2025-01-29-00-00-01.gh-issue-129005.aV_3O8.rst Resolved

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@vstinner
Update Misc/NEWS.d/next/Library/2025-01-29-00-00-01.gh-issue-129005.a…
8f52a54 
…V_3O8.rst
@vstinner
vstinner merged commit e1c4ba9 into python:main Jan 30, 2025
@bedevere-app bedevere-app Bot removed the awaiting merge label Jan 30, 2025
@cmaloney
cmaloney deleted the cmaloney/pyio_bufio_copy branch January 30, 2025 21:58
cmaloney added a commit to cmaloney/cpython that referenced this pull request Jan 31, 2025
@cmaloney
Revert "pythongh-129005: _pyio.BufferedIO remove copy on readall (pyt…
c37b122 
…hon#129454)"

This reverts commit e1c4ba9.
vstinner pushed a commit that referenced this pull request Jan 31, 2025
@cmaloney
Revert "gh-129005: _pyio.BufferedIO remove copy on readall (#129454)" (…
3ebe3d7 
…#129500)

This reverts commit e1c4ba9.
srinivasreddy pushed a commit to srinivasreddy/cpython that referenced this pull request Feb 7, 2025
@cmaloney @srinivasreddy
pythongh-129005: _pyio.BufferedIO remove copy on readall (python#129454)
0a8335e 
Slicing buf and appending chunk would always result in a copy. Commonly
in a readall() there is no already read data in buf, and the amount of
data read may be large, so the copy is expensive.
srinivasreddy pushed a commit to srinivasreddy/cpython that referenced this pull request Feb 7, 2025
@cmaloney @srinivasreddy
Revert "pythongh-129005: _pyio.BufferedIO remove copy on readall (pyt…
ae72910 
…hon#129454)" (python#129500)

This reverts commit e1c4ba9.
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@cmaloney @vstinner
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