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Remove shrink_to_fit from default ToString::to_string implementation. #77997
Remove shrink_to_fit from default ToString::to_string implementation. #77997
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@bors try @rust-timer queue |
Awaiting bors try build completion |
⌛ Trying commit 1a7c78319414969dfbcc67c4afa2b2081f3a3f66 with merge a9f657d64df859414475bb3329cda65b5445193e... |
☀️ Try build successful - checks-actions, checks-azure |
Queued a9f657d64df859414475bb3329cda65b5445193e with parent dd7fc54, future comparison URL. |
Finished benchmarking try commit (a9f657d64df859414475bb3329cda65b5445193e): comparison url. Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up. @bors rollup=never |
That is looking good! |
Co-authored-by: scottmcm <scottmcm@users.noreply.github.com>
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This is a win across the board for performance, and in many cases it's a win in max memory usage, too. A few tests do have higher memory usage, but they don't look unreasonable in absolute terms. I would propose that we merge this as-is, and that we open an issue to do some memory profiling to see where the memory is going in keccak-debug incr-full and inflate-opt full, which could lead us to add back a few targeted |
I strongly suspect that the max-rss <15-20% changes are just noise; if you look at the graphs for the last month (https://perf.rust-lang.org/?start=&end=&absolute=true&stat=max-rss) and scroll down to keccak, you'll see that the data is really noisy. I am on board with merging this though. |
@bors r+ |
📌 Commit 0b06288 has been approved by |
Wow! I never would have guessed it would make that much of a difference! |
☀️ Test successful - checks-actions, checks-azure |
I'm adding relnotes to this (not relnotes-perf), because it is technically a visible semantic change. If you have a |
Pkgsrc changes: * Adjust patches, convert tabs to spaces so that tests pass. * Remove patches which are no longer needed (upstream changed) * Minor adjustments for SunOS, e.g. disable stack probes. * Adjust cargo checksum patching accordingly. * Remove commented-out use of PATCHELF on NetBSD, which doesn't work anyway... Upstream changes: Version 1.49.0 (2020-12-31) ============================ Language ----------------------- - [Unions can now implement `Drop`, and you can now have a field in a union with `ManuallyDrop<T>`.][77547] - [You can now cast uninhabited enums to integers.][76199] - [You can now bind by reference and by move in patterns.][76119] This allows you to selectively borrow individual components of a type. E.g. ```rust #[derive(Debug)] struct Person { name: String, age: u8, } let person = Person { name: String::from("Alice"), age: 20, }; // `name` is moved out of person, but `age` is referenced. let Person { name, ref age } = person; println!("{} {}", name, age); ``` Compiler ----------------------- - [Added tier 1\* support for `aarch64-unknown-linux-gnu`.][78228] - [Added tier 2 support for `aarch64-apple-darwin`.][75991] - [Added tier 2 support for `aarch64-pc-windows-msvc`.][75914] - [Added tier 3 support for `mipsel-unknown-none`.][78676] - [Raised the minimum supported LLVM version to LLVM 9.][78848] - [Output from threads spawned in tests is now captured.][78227] - [Change os and vendor values to "none" and "unknown" for some targets][78951] \* Refer to Rust's [platform support page][forge-platform-support] for more information on Rust's tiered platform support. Libraries ----------------------- - [`RangeInclusive` now checks for exhaustion when calling `contains` and indexing.][78109] - [`ToString::to_string` now no longer shrinks the internal buffer in the default implementation.][77997] - [`ops::{Index, IndexMut}` are now implemented for fixed sized arrays of any length.][74989] Stabilized APIs --------------- - [`slice::select_nth_unstable`] - [`slice::select_nth_unstable_by`] - [`slice::select_nth_unstable_by_key`] The following previously stable methods are now `const`. - [`Poll::is_ready`] - [`Poll::is_pending`] Cargo ----------------------- - [Building a crate with `cargo-package` should now be independently reproducible.][cargo/8864] - [`cargo-tree` now marks proc-macro crates.][cargo/8765] - [Added `CARGO_PRIMARY_PACKAGE` build-time environment variable.] [cargo/8758] This variable will be set if the crate being built is one the user selected to build, either with `-p` or through defaults. - [You can now use glob patterns when specifying packages & targets.][cargo/8752] Compatibility Notes ------------------- - [Demoted `i686-unknown-freebsd` from host tier 2 to target tier 2 support.][78746] - [Macros that end with a semi-colon are now treated as statements even if they expand to nothing.][78376] - [Rustc will now check for the validity of some built-in attributes on enum variants.][77015] Previously such invalid or unused attributes could be ignored. - Leading whitespace is stripped more uniformly in documentation comments, which may change behavior. You read [this post about the changes][rustdoc-ws-post] for more details. - [Trait bounds are no longer inferred for associated types.][79904] Internal Only ------------- These changes provide no direct user facing benefits, but represent significant improvements to the internals and overall performance of rustc and related tools. - [rustc's internal crates are now compiled using the `initial-exec` Thread Local Storage model.][78201] - [Calculate visibilities once in resolve.][78077] - [Added `system` to the `llvm-libunwind` bootstrap config option.][77703] - [Added `--color` for configuring terminal color support to bootstrap.][79004] [75991]: rust-lang/rust#75991 [78951]: rust-lang/rust#78951 [78848]: rust-lang/rust#78848 [78746]: rust-lang/rust#78746 [78376]: rust-lang/rust#78376 [78228]: rust-lang/rust#78228 [78227]: rust-lang/rust#78227 [78201]: rust-lang/rust#78201 [78109]: rust-lang/rust#78109 [78077]: rust-lang/rust#78077 [77997]: rust-lang/rust#77997 [77703]: rust-lang/rust#77703 [77547]: rust-lang/rust#77547 [77015]: rust-lang/rust#77015 [76199]: rust-lang/rust#76199 [76119]: rust-lang/rust#76119 [75914]: rust-lang/rust#75914 [74989]: rust-lang/rust#74989 [79004]: rust-lang/rust#79004 [78676]: rust-lang/rust#78676 [79904]: rust-lang/rust#79904 [cargo/8864]: rust-lang/cargo#8864 [cargo/8765]: rust-lang/cargo#8765 [cargo/8758]: rust-lang/cargo#8758 [cargo/8752]: rust-lang/cargo#8752 [`slice::select_nth_unstable`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.select_nth_unstable [`slice::select_nth_unstable_by`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.select_nth_unstable_by [`slice::select_nth_unstable_by_key`]: https://doc.rust-lang.org/nightly/std/primitive.slice.html#method.select_nth_unstable_by_key [`hint::spin_loop`]: https://doc.rust-lang.org/stable/std/hint/fn.spin_loop.html [`Poll::is_ready`]: https://doc.rust-lang.org/stable/std/task/enum.Poll.html#method.is_ready [`Poll::is_pending`]: https://doc.rust-lang.org/stable/std/task/enum.Poll.html#method.is_pending [rustdoc-ws-post]: https://blog.guillaume-gomez.fr/articles/2020-11-11+New+doc+comment+handling+in+rustdoc
As suggested by @scottmcm on Zulip. shrink_to_fit() seems like the wrong thing to do here in most use cases of to_string(). Would be intereseting to see if it makes any difference in a timer run.
r? @joshtriplett