gh-139871: Add `bytearray.take_bytes([n])` to efficiently extract `bytes` #140128

cmaloney · 2025-10-14T18:20:50Z

Update bytearray to contain a bytes and provide a zero-copy path to "extract" the bytes. This allows making several code paths more efficient.

This does not move any codepaths to make use of this new API. The documentation changes include common code patterns which can be made more efficient with this API.

When just changing bytearray to contain bytes I ran pyperformance on a --with-lto --enable-optimizations --with-static-libpython build (results below) and don't see any major speedups or slowdowns with this; all seems to be in the noise of my machine (Generally changes under 5% or benchmarks that don't touch bytes/bytearray).

pyperformance compare main.json bytearray_bytes.json

main.json

Performance version: 1.11.0
Report on Linux-6.17.1-arch1-1-x86_64-with-glibc2.42
Number of logical CPUs: 32
Start date: 2025-10-14 00:55:52.519236
End date: 2025-10-14 02:23:01.308400

bytearray_bytes.json

Performance version: 1.11.0
Report on Linux-6.17.1-arch1-1-x86_64-with-glibc2.42
Number of logical CPUs: 32
Start date: 2025-10-13 23:22:29.928152
End date: 2025-10-14 00:49:34.467284

+----------------------------------+-----------+----------------------+--------------+------------------------+
| Benchmark                        | main.json | bytearray_bytes.json | Change       | Significance           |
+==================================+===========+======================+==============+========================+
| 2to3                             | 137 ms    | 136 ms               | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_generators                 | 193 ms    | 195 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_cpu_io_mixed          | 285 ms    | 286 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_cpu_io_mixed_tg       | 289 ms    | 290 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager                 | 50.4 ms   | 51.5 ms              | 1.02x slower | Significant (t=-10.40) |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_cpu_io_mixed    | 223 ms    | 225 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_cpu_io_mixed_tg | 263 ms    | 264 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_io              | 370 ms    | 372 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_io_tg           | 380 ms    | 384 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_memoization     | 125 ms    | 126 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_memoization_tg  | 161 ms    | 162 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_eager_tg              | 125 ms    | 125 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_io                    | 366 ms    | 360 ms               | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_io_tg                 | 359 ms    | 361 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_memoization           | 177 ms    | 181 ms               | 1.02x slower | Significant (t=-9.20)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_memoization_tg        | 188 ms    | 189 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_none                  | 151 ms    | 151 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| async_tree_none_tg               | 150 ms    | 151 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| asyncio_tcp                      | 182 ms    | 161 ms               | 1.13x faster | Significant (t=32.85)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| asyncio_tcp_ssl                  | 548 ms    | 553 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| asyncio_websockets               | 342 ms    | 339 ms               | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| bench_mp_pool                    | 7.12 ms   | 7.08 ms              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| bench_thread_pool                | 818 us    | 819 us               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| bpe_tokeniser                    | 2.10 sec  | 2.09 sec             | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| chaos                            | 27.9 ms   | 28.0 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| comprehensions                   | 7.45 us   | 7.24 us              | 1.03x faster | Significant (t=3.27)   |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| connected_components             | 308 ms    | 309 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| coroutines                       | 11.1 ms   | 11.2 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| coverage                         | 33.6 ms   | 34.1 ms              | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| create_gc_cycles                 | 1.16 ms   | 1.16 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| crypto_pyaes                     | 37.1 ms   | 35.6 ms              | 1.04x faster | Significant (t=10.63)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| dask                             | 347 ms    | 351 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| deepcopy                         | 118 us    | 117 us               | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| deepcopy_memo                    | 12.8 us   | 12.7 us              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| deepcopy_reduce                  | 1.32 us   | 1.34 us              | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| deltablue                        | 1.65 ms   | 1.64 ms              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| django_template                  | 17.9 ms   | 17.8 ms              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| docutils                         | 1.19 sec  | 1.20 sec             | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| dulwich_log                      | 19.5 ms   | 19.7 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| fannkuch                         | 184 ms    | 181 ms               | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| float                            | 37.1 ms   | 36.7 ms              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| gc_traversal                     | 3.04 ms   | 2.84 ms              | 1.07x faster | Significant (t=19.48)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| generators                       | 15.9 ms   | 15.3 ms              | 1.04x faster | Significant (t=7.03)   |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| genshi_text                      | 11.3 ms   | 11.2 ms              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| genshi_xml                       | 25.5 ms   | 25.5 ms              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| go                               | 57.6 ms   | 56.7 ms              | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| hexiom                           | 2.92 ms   | 2.88 ms              | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| html5lib                         | 26.0 ms   | 26.5 ms              | 1.02x slower | Significant (t=-9.20)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| json_dumps                       | 4.48 ms   | 4.44 ms              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| json_loads                       | 11.7 us   | 11.7 us              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| k_core                           | 1.41 sec  | 1.42 sec             | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| logging_format                   | 3.27 us   | 3.30 us              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| logging_silent                   | 45.5 ns   | 45.8 ns              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| logging_simple                   | 3.02 us   | 3.01 us              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| mako                             | 6.02 ms   | 6.03 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| many_optionals                   | 473 us    | 478 us               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| mdp                              | 587 ms    | 578 ms               | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| meteor_contest                   | 50.2 ms   | 50.5 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| nbody                            | 54.6 ms   | 52.4 ms              | 1.04x faster | Significant (t=10.72)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| nqueens                          | 41.7 ms   | 40.4 ms              | 1.03x faster | Significant (t=6.79)   |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pathlib                          | 9.77 ms   | 9.73 ms              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pickle                           | 5.99 us   | 6.01 us              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pickle_dict                      | 12.5 us   | 12.8 us              | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pickle_list                      | 1.98 us   | 1.96 us              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pickle_pure_python               | 149 us    | 150 us               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pidigits                         | 111 ms    | 115 ms               | 1.03x slower | Significant (t=-18.53) |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pprint_pformat                   | 737 ms    | 748 ms               | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pprint_safe_repr                 | 362 ms    | 369 ms               | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| pyflate                          | 211 ms    | 205 ms               | 1.03x faster | Significant (t=7.43)   |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| python_startup                   | 7.88 ms   | 7.88 ms              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| python_startup_no_site           | 4.72 ms   | 4.76 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| raytrace                         | 130 ms    | 128 ms               | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| regex_compile                    | 50.0 ms   | 50.2 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| regex_dna                        | 101 ms    | 103 ms               | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| regex_effbot                     | 1.72 ms   | 1.77 ms              | 1.03x slower | Significant (t=-26.42) |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| regex_v8                         | 12.5 ms   | 12.3 ms              | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| richards                         | 20.4 ms   | 20.0 ms              | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| richards_super                   | 23.4 ms   | 22.8 ms              | 1.03x faster | Significant (t=11.36)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| scimark_fft                      | 154 ms    | 153 ms               | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| scimark_lu                       | 55.4 ms   | 57.0 ms              | 1.03x slower | Significant (t=-5.67)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| scimark_monte_carlo              | 32.8 ms   | 32.8 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| scimark_sor                      | 57.8 ms   | 56.9 ms              | 1.02x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| scimark_sparse_mat_mult          | 2.75 ms   | 2.76 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| shortest_path                    | 316 ms    | 318 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| spectral_norm                    | 47.7 ms   | 51.6 ms              | 1.08x slower | Significant (t=-2.01)  |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sphinx                           | 465 ms    | 467 ms               | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sqlglot_v2_normalize             | 50.3 ms   | 50.2 ms              | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sqlglot_v2_optimize              | 24.2 ms   | 24.4 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sqlglot_v2_parse                 | 576 us    | 572 us               | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sqlglot_v2_transpile             | 724 us    | 722 us               | 1.00x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sqlite_synth                     | 1.14 us   | 1.15 us              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| subparsers                       | 20.6 ms   | 20.7 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sympy_expand                     | 181 ms    | 184 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sympy_integrate                  | 8.54 ms   | 8.55 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sympy_str                        | 103 ms    | 105 ms               | 1.02x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| sympy_sum                        | 55.9 ms   | 56.0 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| telco                            | 3.39 ms   | 3.34 ms              | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| tomli_loads                      | 971 ms    | 982 ms               | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| typing_runtime_protocols         | 73.2 us   | 73.6 us              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| unpack_sequence                  | 25.2 ns   | 23.0 ns              | 1.10x faster | Significant (t=7.03)   |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| unpickle                         | 6.99 us   | 7.05 us              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| unpickle_list                    | 2.07 us   | 2.10 us              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| unpickle_pure_python             | 105 us    | 104 us               | 1.01x faster | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| xml_etree_generate               | 40.5 ms   | 40.7 ms              | 1.00x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| xml_etree_iterparse              | 49.7 ms   | 50.4 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| xml_etree_parse                  | 77.2 ms   | 79.1 ms              | 1.02x slower | Significant (t=-16.14) |
+----------------------------------+-----------+----------------------+--------------+------------------------+
| xml_etree_process                | 29.5 ms   | 29.8 ms              | 1.01x slower | Not significant        |
+----------------------------------+-----------+----------------------+--------------+------------------------+

Issue: Add .take_bytes([n]) a zero-copy path from bytearray to bytes #139871

This sets up so the bytes can be "taken" as a byes object without requiring a copy. I ran pyperformance (results below) and don't see any major speedups or slowdowns with this; all seems to be in the noise of my machine. ------ pyperformance compare main.json bytearray_bytes.json -O table main.json ========= Performance version: 1.11.0 Report on Linux-6.17.1-arch1-1-x86_64-with-glibc2.42 Number of logical CPUs: 32 Start date: 2025-10-14 00:55:52.519236 End date: 2025-10-14 02:23:01.308400 bytearray_bytes.json ==================== Performance version: 1.11.0 Report on Linux-6.17.1-arch1-1-x86_64-with-glibc2.42 Number of logical CPUs: 32 Start date: 2025-10-13 23:22:29.928152 End date: 2025-10-14 00:49:34.467284 +----------------------------------+-----------+----------------------+--------------+------------------------+ | Benchmark | main.json | bytearray_bytes.json | Change | Significance | +==================================+===========+======================+==============+========================+ | 2to3 | 137 ms | 136 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_generators | 193 ms | 195 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_cpu_io_mixed | 285 ms | 286 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_cpu_io_mixed_tg | 289 ms | 290 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager | 50.4 ms | 51.5 ms | 1.02x slower | Significant (t=-10.40) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_cpu_io_mixed | 223 ms | 225 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_cpu_io_mixed_tg | 263 ms | 264 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_io | 370 ms | 372 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_io_tg | 380 ms | 384 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_memoization | 125 ms | 126 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_memoization_tg | 161 ms | 162 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_eager_tg | 125 ms | 125 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_io | 366 ms | 360 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_io_tg | 359 ms | 361 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_memoization | 177 ms | 181 ms | 1.02x slower | Significant (t=-9.20) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_memoization_tg | 188 ms | 189 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_none | 151 ms | 151 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | async_tree_none_tg | 150 ms | 151 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | asyncio_tcp | 182 ms | 161 ms | 1.13x faster | Significant (t=32.85) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | asyncio_tcp_ssl | 548 ms | 553 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | asyncio_websockets | 342 ms | 339 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | bench_mp_pool | 7.12 ms | 7.08 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | bench_thread_pool | 818 us | 819 us | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | bpe_tokeniser | 2.10 sec | 2.09 sec | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | chaos | 27.9 ms | 28.0 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | comprehensions | 7.45 us | 7.24 us | 1.03x faster | Significant (t=3.27) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | connected_components | 308 ms | 309 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | coroutines | 11.1 ms | 11.2 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | coverage | 33.6 ms | 34.1 ms | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | create_gc_cycles | 1.16 ms | 1.16 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | crypto_pyaes | 37.1 ms | 35.6 ms | 1.04x faster | Significant (t=10.63) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | dask | 347 ms | 351 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | deepcopy | 118 us | 117 us | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | deepcopy_memo | 12.8 us | 12.7 us | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | deepcopy_reduce | 1.32 us | 1.34 us | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | deltablue | 1.65 ms | 1.64 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | django_template | 17.9 ms | 17.8 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | docutils | 1.19 sec | 1.20 sec | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | dulwich_log | 19.5 ms | 19.7 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | fannkuch | 184 ms | 181 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | float | 37.1 ms | 36.7 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | gc_traversal | 3.04 ms | 2.84 ms | 1.07x faster | Significant (t=19.48) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | generators | 15.9 ms | 15.3 ms | 1.04x faster | Significant (t=7.03) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | genshi_text | 11.3 ms | 11.2 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | genshi_xml | 25.5 ms | 25.5 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | go | 57.6 ms | 56.7 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | hexiom | 2.92 ms | 2.88 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | html5lib | 26.0 ms | 26.5 ms | 1.02x slower | Significant (t=-9.20) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | json_dumps | 4.48 ms | 4.44 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | json_loads | 11.7 us | 11.7 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | k_core | 1.41 sec | 1.42 sec | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | logging_format | 3.27 us | 3.30 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | logging_silent | 45.5 ns | 45.8 ns | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | logging_simple | 3.02 us | 3.01 us | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | mako | 6.02 ms | 6.03 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | many_optionals | 473 us | 478 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | mdp | 587 ms | 578 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | meteor_contest | 50.2 ms | 50.5 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | nbody | 54.6 ms | 52.4 ms | 1.04x faster | Significant (t=10.72) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | nqueens | 41.7 ms | 40.4 ms | 1.03x faster | Significant (t=6.79) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pathlib | 9.77 ms | 9.73 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pickle | 5.99 us | 6.01 us | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pickle_dict | 12.5 us | 12.8 us | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pickle_list | 1.98 us | 1.96 us | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pickle_pure_python | 149 us | 150 us | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pidigits | 111 ms | 115 ms | 1.03x slower | Significant (t=-18.53) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pprint_pformat | 737 ms | 748 ms | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pprint_safe_repr | 362 ms | 369 ms | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | pyflate | 211 ms | 205 ms | 1.03x faster | Significant (t=7.43) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | python_startup | 7.88 ms | 7.88 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | python_startup_no_site | 4.72 ms | 4.76 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | raytrace | 130 ms | 128 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | regex_compile | 50.0 ms | 50.2 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | regex_dna | 101 ms | 103 ms | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | regex_effbot | 1.72 ms | 1.77 ms | 1.03x slower | Significant (t=-26.42) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | regex_v8 | 12.5 ms | 12.3 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | richards | 20.4 ms | 20.0 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | richards_super | 23.4 ms | 22.8 ms | 1.03x faster | Significant (t=11.36) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | scimark_fft | 154 ms | 153 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | scimark_lu | 55.4 ms | 57.0 ms | 1.03x slower | Significant (t=-5.67) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | scimark_monte_carlo | 32.8 ms | 32.8 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | scimark_sor | 57.8 ms | 56.9 ms | 1.02x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | scimark_sparse_mat_mult | 2.75 ms | 2.76 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | shortest_path | 316 ms | 318 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | spectral_norm | 47.7 ms | 51.6 ms | 1.08x slower | Significant (t=-2.01) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sphinx | 465 ms | 467 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sqlglot_v2_normalize | 50.3 ms | 50.2 ms | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sqlglot_v2_optimize | 24.2 ms | 24.4 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sqlglot_v2_parse | 576 us | 572 us | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sqlglot_v2_transpile | 724 us | 722 us | 1.00x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sqlite_synth | 1.14 us | 1.15 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | subparsers | 20.6 ms | 20.7 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sympy_expand | 181 ms | 184 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sympy_integrate | 8.54 ms | 8.55 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sympy_str | 103 ms | 105 ms | 1.02x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | sympy_sum | 55.9 ms | 56.0 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | telco | 3.39 ms | 3.34 ms | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | tomli_loads | 971 ms | 982 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | typing_runtime_protocols | 73.2 us | 73.6 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | unpack_sequence | 25.2 ns | 23.0 ns | 1.10x faster | Significant (t=7.03) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | unpickle | 6.99 us | 7.05 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | unpickle_list | 2.07 us | 2.10 us | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | unpickle_pure_python | 105 us | 104 us | 1.01x faster | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | xml_etree_generate | 40.5 ms | 40.7 ms | 1.00x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | xml_etree_iterparse | 49.7 ms | 50.4 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+ | xml_etree_parse | 77.2 ms | 79.1 ms | 1.02x slower | Significant (t=-16.14) | +----------------------------------+-----------+----------------------+--------------+------------------------+ | xml_etree_process | 29.5 ms | 29.8 ms | 1.01x slower | Not significant | +----------------------------------+-----------+----------------------+--------------+------------------------+

Include/cpython/bytearrayobject.h

vstinner · 2025-10-15T12:57:01Z

Doc/library/stdtypes.rst

+      .. impl-detail::
+
+         CPython implements this as a zero-copy operation making it a very
+         efficient way to make a :class:`bytes` from a :class:`bytearray`.


Only when n is None, no?

vstinner · 2025-10-15T13:03:11Z

Objects/bytearrayobject.c

+        remaining = PyBytes_FromStringAndSize(self->ob_start + to_take,
+                                                    remaining_length + 1);


Suggested change

remaining = PyBytes_FromStringAndSize(self->ob_start + to_take,

remaining_length + 1);

remaining = PyBytes_FromStringAndSize(self->ob_start + to_take,

remaining_length + 1);

vstinner · 2025-10-15T13:05:26Z

Doc/library/stdtypes.rst

+                  buffer = bytearray(1024)
+                  ...
+                  data = buffer.take_bytes()
+                  assert len(buffer) == 0


I suggest removing these assertions. We can trust take_bytes() API, no? :-)

bedevere-app bot added the awaiting review label Oct 14, 2025

bedevere-app bot mentioned this pull request Oct 14, 2025

Add .take_bytes([n]) a zero-copy path from bytearray to bytes #139871

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📜🤖 Added by blurb_it.

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Add bytearray.take_bytes

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cmaloney changed the title ~~gh-139871: Update bytearray to contain PyBytesObject~~ gh-139871: Implement bytearray.take_bytes([n]) to efficiently extract bytes Oct 15, 2025

Merge branch 'main' into bytearray_bytes

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cmaloney changed the title ~~gh-139871: Implement bytearray.take_bytes([n]) to efficiently extract bytes~~ gh-139871: Add bytearray.take_bytes([n]) to efficiently extract bytes Oct 15, 2025

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gh-139871: Add `bytearray.take_bytes([n])` to efficiently extract `bytes` #140128

gh-139871: Add `bytearray.take_bytes([n])` to efficiently extract `bytes` #140128

cmaloney commented Oct 14, 2025 •

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		remaining = PyBytes_FromStringAndSize(self->ob_start + to_take,
		remaining_length + 1);

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gh-139871: Add bytearray.take_bytes([n]) to efficiently extract bytes #140128

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gh-139871: Add bytearray.take_bytes([n]) to efficiently extract bytes #140128

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cmaloney commented Oct 14, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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main.json

bytearray_bytes.json

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gh-139871: Add `bytearray.take_bytes([n])` to efficiently extract `bytes` #140128

gh-139871: Add `bytearray.take_bytes([n])` to efficiently extract `bytes` #140128

cmaloney commented Oct 14, 2025 •

edited

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