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Expose a loom version of std::thread::park #133

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faern opened this issue Apr 25, 2020 · 2 comments · Fixed by #240
Closed

Expose a loom version of std::thread::park #133

faern opened this issue Apr 25, 2020 · 2 comments · Fixed by #240

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@faern
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faern commented Apr 25, 2020

I have a library that uses std::thread::park() and Thread::unpark() for parking one thread when it must wait for another thread to reach a certain point. These tests deadlock under loom. I assume simply because the execution order it's currently evaluating demand that the thread waiting in park() make progress, and not the other ones. And this will obviously never happen.

I have currently gotten the tests to pass by conditionally replacing std::thread::park() with loom::thread::yield_now(). However, I'm not fully sure this tests what I want it to test 🤔

Since I don't know anything about loom internals etc I will put it like this: Would it make sense to expose loom::thread::park and potentially a corresponding loom::thread::Thread?
@Kixunil
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Kixunil commented Feb 3, 2021

I believe yield_now should be correct but clarification would be helpful.

@faern
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faern commented Feb 4, 2021

If so, maybe an alias can be created? It's much easier to conditionally import loom::thread vs std::thread vs having to having more fine grained conditional import over specific functions.

@rmcgibbo rmcgibbo mentioned this issue Oct 15, 2021
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hawkw added a commit that referenced this issue Nov 18, 2021
@hawkw
thread: Add mock versions of thread::park and Thread::unpark
9f17560 
Currently, `loom`'s mock version of `std::thread` does not provide
mocked `std::thread::park` or `std::thread::Thread::unpark` APIs. It
would be nice to be able to use `loom` to test implementations of
synchronization primitives, and other code which uses `thread::park` and
`Thread::unpark`.

Fortunately, the `loom::rt` internals already contain the necessary
primitives to provide simulated versions of these APIs --- they're used
internally in the implementation of the mocked `Condvar` and `Notify`
types. This branch adds APIs for simulating `thread::park` and
`Thread::unpark`.

Closes #133
@hawkw hawkw mentioned this issue Nov 18, 2021
Merged
hawkw added a commit that referenced this issue Nov 22, 2021
@hawkw
thread: Add mock versions of thread::park and Thread::unpark (#240)
d9eac1f 
Currently, `loom`'s mock version of `std::thread` does not provide
mocked `std::thread::park` or `std::thread::Thread::unpark` APIs. It
would be nice to be able to use `loom` to test implementations of
synchronization primitives, and other code which uses `thread::park` and
`Thread::unpark`.

Fortunately, the `loom::rt` internals already contain the necessary
primitives to provide simulated versions of these APIs --- they're used
internally in the implementation of the mocked `Condvar` and `Notify`
types. This branch adds APIs for simulating `thread::park` and
`Thread::unpark`.

Closes #133
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thread: Add mock versions of thread::park and Thread::unpark tokio-rs/loom
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@faern @Kixunil