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Add comments about stdout locking #99742

Merged
merged 1 commit into from
Aug 26, 2022
Merged

Add comments about stdout locking #99742

merged 1 commit into from
Aug 26, 2022

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sigaloid
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This is the source of some confusion regarding the println! macro:

In some of these cases it's not the locking behavior where the bottleneck lies, but it's still mentioned as a surprise when, eg, benchmarking a million println!'s in a very tight loop.

If there's any stylistic problems please feel free to correct me! This is my first contribution and I want to get it right 🦀

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rustbot commented Jul 26, 2022

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

  • Stabilizing library features
  • Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
  • Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
  • Changing public documentation in ways that create new stability guarantees
  • Changing observable runtime behavior of library APIs

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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @kennytm (or someone else) soon.

Please see the contribution instructions for more information.

@rustbot rustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Jul 26, 2022
@rust-highfive rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 26, 2022
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thomcc commented Aug 25, 2022

Looks good. Sorry for the delay.

@bors r+ rollup

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bors commented Aug 25, 2022

📌 Commit fab36d1 has been approved by thomcc

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 25, 2022
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Aug 26, 2022
@Dylan-DPC
Rollup merge of rust-lang#99742 - sigaloid:master, r=thomcc
b464d5f 
Add comments about stdout locking

This is the source of some confusion regarding the `println!` macro:
* https://llogiq.github.io/2017/06/01/perf-pitfalls.html#unbuffered-io
* https://news.ycombinator.com/item?id=18794930
* https://reddit.com/r/rust/comments/5puyx2/why_is_println_so_slow/dcua5g5/
* https://reddit.com/r/rust/comments/ab7hsi/comparing_pythagorean_triples_in_c_d_and_rust/ecy7ql8/

In some of these cases it's not the locking behavior where the bottleneck lies, but it's still mentioned as a surprise when, eg, benchmarking a million `println!`'s in a very tight loop.

If there's any stylistic problems please feel free to correct me! This is my first contribution and I want to get it right 🦀
@Dylan-DPC Dylan-DPC mentioned this pull request Aug 26, 2022
Closed
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Aug 26, 2022
@Dylan-DPC
Rollup merge of rust-lang#99742 - sigaloid:master, r=thomcc
36d2301 
Add comments about stdout locking

This is the source of some confusion regarding the `println!` macro:
* https://llogiq.github.io/2017/06/01/perf-pitfalls.html#unbuffered-io
* https://news.ycombinator.com/item?id=18794930
* https://reddit.com/r/rust/comments/5puyx2/why_is_println_so_slow/dcua5g5/
* https://reddit.com/r/rust/comments/ab7hsi/comparing_pythagorean_triples_in_c_d_and_rust/ecy7ql8/

In some of these cases it's not the locking behavior where the bottleneck lies, but it's still mentioned as a surprise when, eg, benchmarking a million `println!`'s in a very tight loop.

If there's any stylistic problems please feel free to correct me! This is my first contribution and I want to get it right 🦀
@Dylan-DPC Dylan-DPC mentioned this pull request Aug 26, 2022
Closed
Dylan-DPC added a commit to Dylan-DPC/rust that referenced this pull request Aug 26, 2022
@Dylan-DPC
Rollup merge of rust-lang#99742 - sigaloid:master, r=thomcc
de7e652 
Add comments about stdout locking

This is the source of some confusion regarding the `println!` macro:
* https://llogiq.github.io/2017/06/01/perf-pitfalls.html#unbuffered-io
* https://news.ycombinator.com/item?id=18794930
* https://reddit.com/r/rust/comments/5puyx2/why_is_println_so_slow/dcua5g5/
* https://reddit.com/r/rust/comments/ab7hsi/comparing_pythagorean_triples_in_c_d_and_rust/ecy7ql8/

In some of these cases it's not the locking behavior where the bottleneck lies, but it's still mentioned as a surprise when, eg, benchmarking a million `println!`'s in a very tight loop.

If there's any stylistic problems please feel free to correct me! This is my first contribution and I want to get it right 🦀
@Dylan-DPC Dylan-DPC mentioned this pull request Aug 26, 2022
Closed
@GuillaumeGomez GuillaumeGomez mentioned this pull request Aug 26, 2022
Merged
bors added a commit to rust-lang-ci/rust that referenced this pull request Aug 26, 2022
@bors
Auto merge of rust-lang#101037 - GuillaumeGomez:rollup-opn6kj1, r=Gui…
42fa8ac 
…llaumeGomez

Rollup of 8 pull requests

Successful merges:

 - rust-lang#95005 (BTree: evaluate static type-related check at compile time)
 - rust-lang#99742 (Add comments about stdout locking)
 - rust-lang#100128 (Document that `RawWakerVTable` functions must be thread-safe.)
 - rust-lang#100956 (Reduce right-side DOM size)
 - rust-lang#101006 (Fix doc cfg on reexports)
 - rust-lang#101012 (rustdoc: remove unused CSS for `.variants_table`)
 - rust-lang#101023 (rustdoc: remove `type="text/css"` from stylesheet links)
 - rust-lang#101031 (Remove unused build dependency)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup
@bors bors merged commit ae838f7 into rust-lang:master Aug 26, 2022
@rustbot rustbot added this to the 1.65.0 milestone Aug 26, 2022
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