gh-141968: Use `take_bytes` to remove copy in `_pyio.BytesIO.read()` by lgeiger · Pull Request #149850 · python/cpython

lgeiger · 2026-05-14T22:48:56Z

This removes a copy going from bytearray to bytes in _pyio.BytesIO.read().

import timeit
from statistics import mean, stdev

times = timeit.repeat(
    "bio.seek(0); bio.read()",
    setup="import _pyio; bio = _pyio.BytesIO(b'x' * 1024 * 1024)",
    number=50_000,
    repeat=5,
)
print(f"{mean(times) * 1e3:.2f} ± {stdev(times) * 1e3:.2f} ms")

main:    1403.29 ± 14.36 ms
this PR: 785.91 ± 4.27 ms

Issue: Remove bytearray to bytes copies in stdlib using take_bytes #141968

…ad()`

lgeiger · 2026-05-14T22:52:26Z

            b = self._buffer[self._pos : newpos]
            self._pos = newpos
-            return bytes(b)
+            return b.take_bytes()


As far as I can tell b = self._buffer[self._pos : newpos] already copies the bytearray so we can safely use take_bytes()

maurycy · 2026-05-15T09:22:14Z

cc @cmaloney

cmaloney

I think your analysis is correct / the slice already does a copy so take_bytes() is safe in this case.

I've been experimenting to see if there is a way to avoid the temporary bytearray / go straight from the original to final bytes but haven't found anything simpler so far (would save allocating the bytearray head). Can swap in a memoryview but I don't find that simpler, just a different shape.

Could you remove the news file? I added skip news so PR checks should pass. This is just an optimizing refactor and _pyio is not widely used so people are unlikely to see an impact from this. End users only see the C _io implementation. The CPython test suite will run a little faster though which is nice :)

also: How did you spot/find this one? (Wondering if there's more tips and tricks should add to the whatsnew)

cmaloney · 2026-05-15T23:26:47Z

Please don't force push to CPython PRs: https://devguide.python.org/getting-started/pull-request-lifecycle/index.html#don-t-force-push

lgeiger · 2026-05-15T23:29:32Z

Could you remove the news file? I added skip news so PR checks should pass.

Done. I was just trying to make CI happy :)

also: How did you spot/find this one? (Wondering if there's more tips and tricks should add to the whatsnew)

Honestly, I'm not 100% sure anymore. I stumbled upon #149852 by accident some time ago and before making the PR had a quick look at places where bytes() is called on a bytearray using grep which is how I found this one.

lgeiger · 2026-05-15T23:30:32Z

Please don't force push to CPython PRs: https://devguide.python.org/getting-started/pull-request-lifecycle/index.html#don-t-force-push

Sorry, will keep in mind for the future. Just force pushed to remove the last two commits which added the news entry.

bedevere-bot · 2026-05-19T01:17:50Z

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot iOS ARM64 Simulator 3.x (tier-3) has failed when building commit 43c3438.

What do you need to do:

Don't panic.
Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
Go to the page of the buildbot that failed (https://buildbot.python.org/#/builders/1380/builds/6678) and take a look at the build logs.
Check if the failure is related to this commit (43c3438) or if it is a false positive.
If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/#/builders/1380/builds/6678

Summary of the results of the build (if available):

Click to see traceback logs

remote: Enumerating objects: 4, done.        
remote: Counting objects:  33% (1/3)        
remote: Counting objects:  66% (2/3)        
remote: Counting objects: 100% (3/3)        
remote: Counting objects: 100% (3/3), done.        
remote: Compressing objects:  33% (1/3)        
remote: Compressing objects:  66% (2/3)        
remote: Compressing objects: 100% (3/3)        
remote: Compressing objects: 100% (3/3), done.        
remote: Total 4 (delta 0), reused 0 (delta 0), pack-reused 1 (from 1)        
From https://github.com/python/cpython
 * branch                    main       -> FETCH_HEAD
Note: switching to '43c3438a2a31cef152e5fa1172983b4d3e4d8a58'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

HEAD is now at 43c3438a2a3 gh-141968: Use `take_bytes` to remove copy in `_pyio.BytesIO.read()` (#149850)
Switched to and reset branch 'main'

configure: WARNING: no system libmpdec found; falling back to pure-Python version for the decimal module
configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.

configure: WARNING: unrecognized options: --with-system-libmpdec
configure: WARNING: unrecognized options: --with-system-libmpdec
configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.
ld: warning: ignoring duplicate libraries: '-lm'
In file included from ../../Modules/_remote_debugging/module.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/gc_stats.c:7:
In file included from ../../Modules/_remote_debugging/gc_stats.h:14:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/object_reading.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | 1_ warning generated.
Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/code_objects.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/frames.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/frame_cache.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
In file included from ../../Modules/_remote_debugging/threads.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
In file included from ../../Modules/_remote_debugging/asyncio.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/binary_io_reader.c:13:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/binary_io_writer.c:13:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/subprocess.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../Modules/_remote_debugging/subprocess.c:100:1: warning: unused function 'find_children_bfs' [-Wunused-function]
  100 | find_children_bfs(pid_t target_pid, int recursive,
      | ^~~~~~~~~~~~~~~~~
2 warnings generated.
In file included from ../../Modules/_remote_debugging/interpreters.c:7:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
1 warning generated.
1 warning generated.
ld: warning: ignoring duplicate libraries: '-lm'
configure: WARNING: unrecognized options: --with-system-libmpdec
configure: WARNING: unrecognized options: --with-system-libmpdec
configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.
ld: warning: ignoring duplicate libraries: '-lm'
In file included from ../../Modules/_remote_debugging/gc_stats.c:7:
In file included from ../../Modules/_remote_debugging/gc_stats.h:14:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/module.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/object_reading.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/code_objects.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/frames.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/frame_cache.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
1 warning generated.
In file included from ../../Modules/_remote_debugging/threads.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/binary_io_writer.c:13:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/asyncio.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/binary_io_reader.c:13:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/subprocess.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../Modules/_remote_debugging/subprocess.c:100:1: warning: unused function 'find_children_bfs' [-Wunused-function]
  100 | find_children_bfs(pid_t target_pid, int recursive,
      | ^~~~~~~~~~~~~~~~~
2 warnings generated.
In file included from ../../Modules/_remote_debugging/interpreters.c:7:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
1 warning generated.
1 warning generated.
ld: warning: ignoring duplicate libraries: '-lm'
configure: WARNING: unrecognized options: --with-system-libmpdec
configure: WARNING: x86_64-apple-ios-simulator/clang is not supported
configure: WARNING: unrecognized options: --with-system-libmpdec
configure: WARNING: pkg-config is missing. Some dependencies may not be detected correctly.
configure: WARNING:

Platform "x86_64-apple-ios-simulator" with compiler "clang" is not supported by the
CPython core team, see https://peps.python.org/pep-0011/ for more information.

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(brc.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(dynamic_annotations.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(gc_free_threading.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(index_pool.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(jit.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(jit_publish.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(optimizer_analysis.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(optimizer_symbols.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(pystats.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(stackrefs.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(uniqueid.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(perf_jit_trampoline.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libpython3.16.a(jit_unwind.o) has no symbols
ld: warning: ignoring duplicate libraries: '-lm'
In file included from ../../Modules/_remote_debugging/gc_stats.c:7:
In file included from ../../Modules/_remote_debugging/gc_stats.h:14:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/module.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/object_reading.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/code_objects.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/frames.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/frame_cache.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
In file included from ../../Modules/_remote_debugging/threads.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
In file included from ../../Modules/_remote_debugging/binary_io_writer.c:13:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
In file included from ../../Modules/_remote_debugging/asyncio.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/binary_io_reader.c:13:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../../Modules/_remote_debugging/subprocess.c:8:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../Modules/_remote_debugging/subprocess.c:100:1: warning: unused function 'find_children_bfs' [-Wunused-function]
  100 | find_children_bfs(pid_t target_pid, int recursive,
      | ^~~~~~~~~~~~~~~~~
2 warnings generated.
In file included from ../../Modules/_remote_debugging/interpreters.c:7:
In file included from ../../Modules/_remote_debugging/_remote_debugging.h:34:
../../Modules/_remote_debugging/../../Python/remote_debug.h:165:1: warning: unused function '_Py_RemoteDebug_ValidatePyRuntimeCookie' [-Wunused-function]
  165 | _Py_RemoteDebug_ValidatePyRuntimeCookie(proc_handle_t *handle, uintptr_t address)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
1 warning generated.
1 warning generated.
1 warning generated.
ld: warning: ignoring duplicate libraries: '-lm'

--- xcodebuild: WARNING: Using the first of multiple matching destinations:
{ platform:iOS Simulator, id:4F9AFDE7-A49A-46AD-B161-FCA22E48EA55, OS:18.3.1, name:iPhone SE (3rd generation) }
{ platform:iOS Simulator, id:4F9AFDE7-A49A-46AD-B161-FCA22E48EA55, OS:18.3.1, name:iPhone SE (3rd generation) }

cmaloney · 2026-05-19T01:32:43Z

CI failure unrelated to this change

pythongh-141968: Use take_bytes to remove copy in `_pyio.BytesIO.re…

a61f732

…ad()`

bedevere-app Bot added the awaiting review label May 14, 2026

bedevere-app Bot mentioned this pull request May 14, 2026

Remove bytearray to bytes copies in stdlib using take_bytes #141968

Closed

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lgeiger commented May 14, 2026

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Comment thread Misc/NEWS.d/next/Library/2026-05-14-22-50-54.gh-issue-141968.eRqeCL.rst Outdated

lgeiger force-pushed the pyio-take-bytes branch 2 times, most recently from d67f989 to d32d3b0 Compare May 14, 2026 23:23

cmaloney added the skip news label May 15, 2026

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lgeiger force-pushed the pyio-take-bytes branch from d32d3b0 to a61f732 Compare May 15, 2026 23:23

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bedevere-app Bot added awaiting core review and removed awaiting review labels May 15, 2026

Merge branch 'main' into pyio-take-bytes

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emmatyping approved these changes May 18, 2026

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bedevere-app Bot added awaiting merge and removed awaiting core review labels May 18, 2026

Merge branch 'main' into pyio-take-bytes

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emmatyping enabled auto-merge (squash) May 19, 2026 00:03

emmatyping merged commit 43c3438 into python:main May 19, 2026
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bedevere-app Bot removed the awaiting merge label May 19, 2026

lgeiger deleted the pyio-take-bytes branch May 19, 2026 01:00

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gh-141968: Use `take_bytes` to remove copy in `_pyio.BytesIO.read()`#149850

gh-141968: Use `take_bytes` to remove copy in `_pyio.BytesIO.read()`#149850
emmatyping merged 3 commits into
python:mainfrom
lgeiger:pyio-take-bytes

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