thread parking: fix docs and examples #145895
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rustbot
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The Miri subtree was changed cc @rust-lang/miri |
RalfJung
commented
Aug 26, 2025
| /// use std::time::Duration; | ||
| /// | ||
| /// let flag = Arc::new(AtomicBool::new(false)); | ||
| /// let flag2 = Arc::clone(&flag); |
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I switches this from Arc to static as I find that easier to read.
| /// while !flag2.load(Ordering::Relaxed) { | ||
| /// println!("Parking thread"); | ||
| /// while !FLAG.load(Ordering::Acquire) { | ||
| /// // `eprintln!` does not do any thread parking internally so we can safely call it here. |
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I don't think we actually guarantee that eprintln! does not park, so this comment is dubious.
| /// // We want to wait until the flag is set. We *could* just spin, but using | ||
| /// // park/unpark is more efficient. | ||
| /// while !flag2.load(Ordering::Relaxed) { | ||
| /// println!("Parking thread"); | ||
| /// while !FLAG.load(Ordering::Acquire) { |
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I used release/acquire orderings for my variables since generally IMO one should only used relaxed when it is quite obviously the right thing, and I don't think that's obvious here at all. I then also changed the flag for consistency. If this flag indicates that some work was done (as flags often do), then it really should use release/acquire.
RossSmyth
suggested changes
Aug 26, 2025
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Fixes #145816
r? @joboet
Cc @m-ou-se @Amanieu