Pin Futures in #[tokio::test] to stack by Thomasdezeeuw · Pull Request #5205 · tokio-rs/tokio (original) (raw)
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Thomas de Zeeuw added 2 commits
This reduces the amount of copies of the Runtime::block_on and related functions the compiler has to generate and LLVM process. We've seen it reduce the compilation time of our tests (some 1900 of them) from 40s down to 12s, with no impact on the runtime of tests.
Below is an output of llvm-lines for our tests.
Before:
Lines Copies Function name
8954414 156577 (TOTAL) 984626 (11.0%, 11.0%) 9289 (5.9%, 5.9%) std::thread::local::LocalKey::try_with 648093 (7.2%, 18.2%) 1857 (1.2%, 7.1%) tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}} 557100 (6.2%, 24.5%) 3714 (2.4%, 9.5%) tokio::park::thread::CachedParkThread::block_on 551679 (6.2%, 30.6%) 7430 (4.7%, 14.2%) tokio::coop::with_budget::{{closure}} 514389 (5.7%, 36.4%) 3714 (2.4%, 16.6%) tokio::runtime::scheduler::current_thread::Context::enter 326832 (3.6%, 40.0%) 1857 (1.2%, 17.8%) tokio::runtime::scheduler::current_thread::CurrentThread::block_on 291549 (3.3%, 43.3%) 1857 (1.2%, 19.0%) tokio::runtime::scheduler::current_thread::CoreGuard::enter 261907 (2.9%, 46.2%) 7430 (4.7%, 23.7%) tokio::coop::budget 189468 (2.1%, 48.3%) 7430 (4.7%, 28.5%) tokio::coop::with_budget 137418 (1.5%, 49.8%) 3714 (2.4%, 30.8%) tokio::runtime::enter::Enter::block_on 126276 (1.4%, 51.3%) 1857 (1.2%, 32.0%) tokio::runtime::Runtime::block_on 124419 (1.4%, 52.6%) 1857 (1.2%, 33.2%) tokio::macros::scoped_tls::ScopedKey::set 118897 (1.3%, 54.0%) 3715 (2.4%, 35.6%) core::option::Option::or_else 111420 (1.2%, 55.2%) 1857 (1.2%, 36.8%) tokio::runtime::scheduler::current_thread::CurrentThread::block_on::{{closure}} 109408 (1.2%, 56.4%) 2105 (1.3%, 38.1%) <core::future::from_generator::GenFuture as core::future::future::Future>::poll 105893 (1.2%, 57.6%) 9289 (5.9%, 44.0%) std::thread::local::LocalKey::with 96564 (1.1%, 58.7%) 1857 (1.2%, 45.2%) tokio::runtime::scheduler::current_thread::Context::run_task 90993 (1.0%, 59.7%) 7428 (4.7%, 50.0%) tokio::runtime::scheduler::current_thread::CoreGuard::block_on::{{closure}}::{{closure}} 90515 (1.0%, 60.7%) 2105 (1.3%, 51.3%) core::pin::Pin<&mut T>::map_unchecked_mut 89136 (1.0%, 61.7%) 1857 (1.2%, 52.5%) tokio::runtime::scheduler::multi_thread::MultiThread::block_on
After:
Lines Copies Function name
3188618 41634 (TOTAL) 109408 (3.4%, 3.4%) 2105 (5.1%, 5.1%) <core::future::from_generator::GenFuture as core::future::future::Future>::poll 90515 (2.8%, 6.3%) 2105 (5.1%, 10.1%) core::pin::Pin<&mut T>::map_unchecked_mut 56220 (1.8%, 8.0%) 1874 (4.5%, 14.6%) alloc::boxed::Box::pin 48333 (1.5%, 9.5%) 2179 (5.2%, 19.8%) core::ops::function::FnOnce::call_once 28587 (0.9%, 10.4%) 1 (0.0%, 19.8%) XXXXXXXXXXXXXXXXXXX 18730 (0.6%, 11.0%) 1873 (4.5%, 24.3%) alloc::boxed::Box<T,A>::into_pin 16190 (0.5%, 11.5%) 2 (0.0%, 24.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 15870 (0.5%, 12.0%) 2 (0.0%, 24.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 15250 (0.5%, 12.5%) 1 (0.0%, 24.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXX 12801 (0.4%, 12.9%) 2 (0.0%, 24.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 12801 (0.4%, 13.3%) 2 (0.0%, 24.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 12630 (0.4%, 13.7%) 2105 (5.1%, 29.4%) <core::future::from_generator::GenFuture as core::future::future::Future>::poll::{{closure}} 12613 (0.4%, 14.1%) 2 (0.0%, 29.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 12613 (0.4%, 14.5%) 2 (0.0%, 29.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 12613 (0.4%, 14.9%) 2 (0.0%, 29.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 12613 (0.4%, 15.3%) 2 (0.0%, 29.4%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 11395 (0.4%, 15.7%) 96 (0.2%, 29.7%) alloc::alloc::box_free 11364 (0.4%, 16.0%) 1891 (4.5%, 34.2%) <T as core::convert::Into>::into 11238 (0.4%, 16.4%) 1873 (4.5%, 38.7%) alloc::boxed::<impl core::convert::From<alloc::boxed::Box<T,A>> for core::pin::Pin<alloc::boxed::Box<T,A>>>::from 10735 (0.3%, 16.7%) 2 (0.0%, 38.7%) XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
Note that I have replaced our test functions with XXX. As you can clearly see they're not in the top 20 in the before output, while they're in the after oput.
Further note that the amount of copies have been reduced from 156577 to 41634.
Box Futures in #[tokio::test] Pin Futures in #[tokio::test] to stack
