process: use blocking threadpool for child stdio I/O #4824

ipetkov · 2022-07-11T22:36:38Z

We can't mix async pipes and child process stdio on Windows. This switches our Windows process implementation to use the blocking threadpool instead of using an async named pipe as we did in the past.

Refs #4802

tokio/Cargo.toml

tokio/src/lib.rs

tokio/src/io/poll_evented.rs

tokio/src/process/windows.rs

tokio/src/process/mod.rs

Darksonn · 2022-07-22T13:08:50Z

tokio/src/process/windows.rs

+#[derive(Debug)]
+pub(crate) struct ChildStdio {
+    // Used for accessing the raw handle, even if the io version is busy
+    raw: Arc<StdFile>,
+    // For doing I/O operations asynchronously
+    io: Blocking<ArcFile>,
+}


It seems like you could drop the Arc stuff if you just stored the raw handle next to the io field.

std::process::Stdio wants ownership of the handle (and will close it on drop) which might cause issues if the handle is still being written to in the background. Using the Arc allows us to potentially avoid a syscall to duplicate the handle if it doesn't have any pending I/O on it

You could implement a try_unwrap on the Blocking type to get the same behavior without the Arc. But I don't mind either way, so I will approve it and let you decide if you want to implement that.

I did consider adding try_unwrap to Blocking, the tricky bit is that it moves the handle to and from the blocking threadpool, so if there is a pending I/O operation we cannot access anything. The conversion from ChildStd* to Stdio are synchronous, so we cannot even internally .await things. Hence the Arc approach allows us to at least clone the handle if needed

I'm going to leave it as is for now since we can always revisit it later as needed. Thanks for the review!

This PR contains the following updates: | Package | Type | Update | Change | |---|---|---|---| | [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dependencies | minor | `1.20.1` -> `1.21.0` | | [tokio](https://tokio.rs) ([source](https://github.com/tokio-rs/tokio)) | dev-dependencies | minor | `1.20.1` -> `1.21.0` | --- ### Release Notes <details> <summary>tokio-rs/tokio</summary> ### [`v1.21.0`](https://github.com/tokio-rs/tokio/releases/tag/tokio-1.21.0) [Compare Source](tokio-rs/tokio@tokio-1.20.1...tokio-1.21.0) ##### 1.21.0 (September 2, 2022) This release is the first release of Tokio to intentionally support WASM. The `sync,macros,io-util,rt,time` features are stabilized on WASM. Additionally the wasm32-wasi target is given unstable support for the `net` feature. ##### Added - net: add `device` and `bind_device` methods to TCP/UDP sockets ([#4882]) - net: add `tos` and `set_tos` methods to TCP and UDP sockets ([#4877]) - net: add security flags to named pipe `ServerOptions` ([#4845]) - signal: add more windows signal handlers ([#4924]) - sync: add `mpsc::Sender::max_capacity` method ([#4904]) - sync: implement Weak version of `mpsc::Sender` ([#4595]) - task: add `LocalSet::enter` ([#4765]) - task: stabilize `JoinSet` and `AbortHandle` ([#4920]) - tokio: add `track_caller` to public APIs ([#4805], [#4848], [#4852]) - wasm: initial support for `wasm32-wasi` target ([#4716]) ##### Fixed - miri: improve miri compatibility by avoiding temporary references in `linked_list::Link` impls ([#4841]) - signal: don't register write interest on signal pipe ([#4898]) - sync: add `#[must_use]` to lock guards ([#4886]) - sync: fix hang when calling `recv` on closed and reopened broadcast channel ([#4867]) - task: propagate attributes on task-locals ([#4837]) ##### Changed - fs: change panic to error in `File::start_seek` ([#4897]) - io: reduce syscalls in `poll_read` ([#4840]) - process: use blocking threadpool for child stdio I/O ([#4824]) - signal: make `SignalKind` methods const ([#4956]) ##### Internal changes - rt: extract `basic_scheduler::Config` ([#4935]) - rt: move I/O driver into `runtime` module ([#4942]) - rt: rename internal scheduler types ([#4945]) ##### Documented - chore: fix typos and grammar ([#4858], [#4894], [#4928]) - io: fix typo in `AsyncSeekExt::rewind` docs ([#4893]) - net: add documentation to `try_read()` for zero-length buffers ([#4937]) - runtime: remove incorrect panic section for `Builder::worker_threads` ([#4849]) - sync: doc of `watch::Sender::send` improved ([#4959]) - task: add cancel safety docs to `JoinHandle` ([#4901]) - task: expand on cancellation of `spawn_blocking` ([#4811]) - time: clarify that the first tick of `Interval::tick` happens immediately ([#4951]) ##### Unstable - rt: add unstable option to disable the LIFO slot ([#4936]) - task: fix incorrect signature in `Builder::spawn_on` ([#4953]) - task: make `task::Builder::spawn*` methods fallible ([#4823]) [#4595]: tokio-rs/tokio#4595 [#4716]: tokio-rs/tokio#4716 [#4765]: tokio-rs/tokio#4765 [#4805]: tokio-rs/tokio#4805 [#4811]: tokio-rs/tokio#4811 [#4823]: tokio-rs/tokio#4823 [#4824]: tokio-rs/tokio#4824 [#4837]: tokio-rs/tokio#4837 [#4840]: tokio-rs/tokio#4840 [#4841]: tokio-rs/tokio#4841 [#4845]: tokio-rs/tokio#4845 [#4848]: tokio-rs/tokio#4848 [#4849]: tokio-rs/tokio#4849 [#4852]: tokio-rs/tokio#4852 [#4858]: tokio-rs/tokio#4858 [#4867]: tokio-rs/tokio#4867 [#4877]: tokio-rs/tokio#4877 [#4882]: tokio-rs/tokio#4882 [#4886]: tokio-rs/tokio#4886 [#4893]: tokio-rs/tokio#4893 [#4894]: tokio-rs/tokio#4894 [#4897]: tokio-rs/tokio#4897 [#4898]: tokio-rs/tokio#4898 [#4901]: tokio-rs/tokio#4901 [#4904]: tokio-rs/tokio#4904 [#4920]: tokio-rs/tokio#4920 [#4924]: tokio-rs/tokio#4924 [#4928]: tokio-rs/tokio#4928 [#4935]: tokio-rs/tokio#4935 [#4936]: tokio-rs/tokio#4936 [#4937]: tokio-rs/tokio#4937 [#4942]: tokio-rs/tokio#4942 [#4945]: tokio-rs/tokio#4945 [#4951]: tokio-rs/tokio#4951 [#4953]: tokio-rs/tokio#4953 [#4956]: tokio-rs/tokio#4956 [#4959]: tokio-rs/tokio#4959 </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. --- - [ ] If you want to rebase/retry this PR, click this checkbox. --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Co-authored-by: cabr2-bot <cabr2.help@gmail.com> Reviewed-on: https://codeberg.org/Calciumdibromid/CaBr2/pulls/1532 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>

process: use blocking threadpool for child stdio I/O

9f03276

ipetkov added A-tokio Area: The main tokio crate M-process Module: tokio/process labels Jul 11, 2022

github-actions bot added the R-loom Run loom tests on this PR label Jul 11, 2022

ipetkov commented Jul 11, 2022

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ipetkov requested a review from Noah-Kennedy July 11, 2022 22:37

Darksonn reviewed Jul 13, 2022

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tokio/src/lib.rs Outdated Show resolved Hide resolved

Reduce handle duplication in the happy path

74a78e6

ipetkov force-pushed the ivan/windows-process-stdio branch from 4a11f75 to 74a78e6 Compare July 20, 2022 22:50

ipetkov marked this pull request as ready for review July 20, 2022 22:51

Darksonn reviewed Jul 21, 2022

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tokio/src/io/poll_evented.rs Show resolved Hide resolved

tokio/src/process/windows.rs Outdated Show resolved Hide resolved

Simplify pin handling

f5c23b1

Darksonn reviewed Jul 22, 2022

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Remove more pin_project

065f28d

Darksonn approved these changes Jul 23, 2022

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ipetkov merged commit 1578575 into master Jul 23, 2022

ipetkov deleted the ivan/windows-process-stdio branch July 23, 2022 17:40

ipetkov mentioned this pull request Jul 23, 2022

Cannot run any command with piped stdin with Nightly toolchain #4670

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Darksonn mentioned this pull request Sep 1, 2022

chore: prepare Tokio v1.21.0 #4967

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process: use blocking threadpool for child stdio I/O #4824

process: use blocking threadpool for child stdio I/O #4824

ipetkov commented Jul 11, 2022

Darksonn Jul 22, 2022

ipetkov Jul 22, 2022

Darksonn Jul 23, 2022

ipetkov Jul 23, 2022

process: use blocking threadpool for child stdio I/O #4824

process: use blocking threadpool for child stdio I/O #4824

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ipetkov commented Jul 11, 2022

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