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fs: Warn about performance pitfall #4762

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merged 4 commits into from
Jun 15, 2022
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@NotAFile NotAFile commented Jun 9, 2022

Motivation

Straightforwardly porting synchronous filesystem code to tokio::fs can cause unexpected performance issues (and with tracing, memory issues too), if one is not aware of the implications of adapters spawning a new task for every operation.

Solution

Document the pitfall and provide a replacement example for the common action of reading a file line by line.

@Darksonn Darksonn added T-docs Topic: documentation A-tokio Area: The main tokio crate M-fs Module: tokio/fs labels Jun 10, 2022
@Darksonn Darksonn merged commit d487c1c into tokio-rs:master Jun 15, 2022
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Thanks!

crapStone pushed a commit to Calciumdibromid/CaBr2 that referenced this pull request Jul 18, 2022
This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dependencies | minor | `1.19.2` -> `1.20.0` |
| [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dev-dependencies | minor | `1.19.2` -> `1.20.0` |

---

### Release Notes

<details>
<summary>tokio-rs/tokio</summary>

### [`v1.20.0`](https://github.com/tokio-rs/tokio/releases/tag/tokio-1.20.0)

[Compare Source](tokio-rs/tokio@tokio-1.19.2...tokio-1.20.0)

##### 1.20.0 (July 12, 2022)

##### Added

-   tokio: add track_caller to public APIs ([#&#8203;4772], [#&#8203;4791], [#&#8203;4793], [#&#8203;4806], [#&#8203;4808])
-   sync: Add `has_changed` method to `watch::Ref` ([#&#8203;4758])

##### Changed

-   time: remove `src/time/driver/wheel/stack.rs` ([#&#8203;4766])
-   rt: clean up arguments passed to basic scheduler ([#&#8203;4767])
-   net: be more specific about winapi features ([#&#8203;4764])
-   tokio: use const initialized thread locals where possible ([#&#8203;4677])
-   task: various small improvements to LocalKey ([#&#8203;4795])

##### Fixed

##### Documented

-   fs: warn about performance pitfall ([#&#8203;4762])
-   chore: fix spelling ([#&#8203;4769])
-   sync: document spurious failures in oneshot ([#&#8203;4777])
-   sync: add warning for watch in non-Send futures ([#&#8203;4741])
-   chore: fix typo ([#&#8203;4798])

##### Unstable

-   joinset: rename `join_one` to `join_next` ([#&#8203;4755])
-   rt: unhandled panic config for current thread rt ([#&#8203;4770])

[#&#8203;4677]: tokio-rs/tokio#4677

[#&#8203;4741]: tokio-rs/tokio#4741

[#&#8203;4755]: tokio-rs/tokio#4755

[#&#8203;4758]: tokio-rs/tokio#4758

[#&#8203;4762]: tokio-rs/tokio#4762

[#&#8203;4764]: tokio-rs/tokio#4764

[#&#8203;4766]: tokio-rs/tokio#4766

[#&#8203;4767]: tokio-rs/tokio#4767

[#&#8203;4769]: tokio-rs/tokio#4769

[#&#8203;4770]: tokio-rs/tokio#4770

[#&#8203;4772]: tokio-rs/tokio#4772

[#&#8203;4777]: tokio-rs/tokio#4777

[#&#8203;4791]: tokio-rs/tokio#4791

[#&#8203;4793]: tokio-rs/tokio#4793

[#&#8203;4795]: tokio-rs/tokio#4795

[#&#8203;4798]: tokio-rs/tokio#4798

[#&#8203;4806]: tokio-rs/tokio#4806

[#&#8203;4808]: tokio-rs/tokio#4808

</details>

---

### Configuration

📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about these updates again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, click this checkbox.

---

This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiIzMi4xMTEuMSIsInVwZGF0ZWRJblZlciI6IjMyLjExMS4xIn0=-->

Co-authored-by: cabr2-bot <cabr2.help@gmail.com>
Reviewed-on: https://codeberg.org/Calciumdibromid/CaBr2/pulls/1458
Reviewed-by: crapStone <crapstone@noreply.codeberg.org>
Co-authored-by: Calciumdibromid Bot <cabr2_bot@noreply.codeberg.org>
Co-committed-by: Calciumdibromid Bot <cabr2_bot@noreply.codeberg.org>
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