Rust `std::time::Instant` "panicked at 'supplied instant is later than self"

Question

I'm trying to get a simple timer set up in rust that returns true at a certain frequency.

#[derive(Clone, Debug)]
pub struct IntervalTimer {
    pub period: Duration,
    pub delta: Instant,
}

impl IntervalTimer {
    pub fn new(period: Duration) -> Self {
        let delta = Instant::now();
        Self { period, delta }
    }

    /// Returns true if the interval between calls has exceeded the period
    pub fn ready(&mut self) -> bool {
        if self.delta.elapsed() < self.period {
            false
        } else {
            self.delta = self.delta + self.period;
            true
        }
    }
}

For some reason, this seems to consistently panic when using std::time::Instant within rayon tasks (running in Legion ECS if that matters).

This was the only other post with information in it that gives the same info but it came down to using an unusual kernel. I'm just using Ubuntu 18.04 with nothing unusual set up.

• https://github.com/rust-lang/rust/issues/59673

Additionally, I've tried multiple machines but the same error occurs witht he code.

Is this something to do with using std::time::Instant and rayon?

thread 'thread '<unnamed><unnamed>' panicked at '' panicked at 'supplied instant is later than self', src/libstd/time.rs:263:9
stack backtrace:
supplied instant is later than self', src/libstd/time.rs:263:9
   0:     0x5574c8e3b9e4 - backtrace::backtrace::libunwind::trace::hc1c4a1d8ad423b97
                               at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/libunwind.rs:86
   1:     0x5574c8e3b9e4 - backtrace::backtrace::trace_unsynchronized::h82274781060cb056
                               at /cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.46/src/backtrace/mod.rs:66
   2:     0x5574c8e3b9e4 - std::sys_common::backtrace::_print_fmt::h2a45d89b653a4da8
                               at src/libstd/sys_common/backtrace.rs:78
   3:     0x5574c8e3b9e4 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h41a0a93ab85e6aa1
                               at src/libstd/sys_common/backtrace.rs:59
   4:     0x5574c8e64b2c - core::fmt::write::hdaea18585065a96d
                               at src/libcore/fmt/mod.rs:1069
   5:     0x5574c8e34743 - std::io::Write::write_fmt::h0cea70c809005252
                               at src/libstd/io/mod.rs:1504
   6:     0x5574c8e3e7a5 - std::sys_common::backtrace::_print::hd95f9978cc145ca4
                               at src/libstd/sys_common/backtrace.rs:62
   7:     0x5574c8e3e7a5 - std::sys_common::backtrace::print::hfb25ca2291be47d0
                               at src/libstd/sys_common/backtrace.rs:49
   8:     0x5574c8e3e7a5 - std::panicking::default_hook::{{closure}}::h44f76cee5dc8591c
                               at src/libstd/panicking.rs:198
   9:     0x5574c8e3e4e2 - std::panicking::default_hook::h198e1a712910f1e6
                               at src/libstd/panicking.rs:218
  10:     0x5574c8e3ee02 - std::panicking::rust_panic_with_hook::hc0b4730bb8013f9d
                               at src/libstd/panicking.rs:511
  11:     0x5574c8e3e9eb - rust_begin_unwind
                               at src/libstd/panicking.rs:419
  12:     0x5574c8e62921 - core::panicking::panic_fmt::h1ac71ad045d55416
                               at src/libcore/panicking.rs:111
  13:     0x5574c8e626b3 - core::option::expect_failed::h7baa1c60813ff0e3
                               at src/libcore/option.rs:1260
  14:     0x5574c8e3b3e5 - core::option::Option<T>::expect::h306e330bd810d3ba
                               at /rustc/49cae55760da0a43428eba73abcb659bb70cf2e4/src/libcore/option.rs:347
  15:     0x5574c8e3b3e5 - std::time::Instant::duration_since::hba1f841dfadd1cd2
                               at src/libstd/time.rs:263
  16:     0x5574c8e3b3e5 - <std::time::Instant as core::ops::arith::Sub>::sub::h73cd3ea7a55658e1
                               at src/libstd/time.rs:390
  17:     0x5574c8e3b3e5 - std::time::Instant::elapsed::h67e85e1d84cb14d0
                               at src/libstd/time.rs:327
  18:     0x5574c8bfe09f - locus_sim_engine::utils::interval_timer::IntervalTimer::ready::h7569661c5fd39089
                               at src/utils/interval_timer.rs:17
  19:     0x5574c8bfe09f - locus_sim_engine::system::laser_scan::single_laser_scan::h671b01a54874470e
                               at src/system/laser_scan.rs:63
  20:     0x5574c8bf074d - locus_sim_engine::system::laser_scan::laser_scan::{{closure}}::h1deba93ec7418c4d
                               at src/system/laser_scan.rs:50
  21:     0x5574c8bf074d - core::ops::function::impls::<impl core::ops::function::Fn<A> for &F>::call::h96b179e6c0dd1ac0
                               at /home/michael/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/ops/function.rs:242
  22:     0x5574c8bf074d - core::ops::function::impls::<impl core::ops::function::FnMut<A> for &F>::call_mut::h4f8d7ff151c5feb5
                               at /home/michael/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/ops/function.rs:252
  23:     0x5574c8a918f8 - <locus_sim_api::motor_server::MotorServer<T> as tower_service::Service<http::request::Request<B>>>::call::{{closure}}::hf5b46adb51805ebe                                         
                               at /home/michael/locus_dev/src/locus_sim_engine/target/release/build/locus-sim-api-4d28cb656733f563/out/locus_sim_api.rs:531                                                 
  24:     0x5574c8a918f8 - <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll::h9798dbde38a1f607                                                                            
                               at /home/michael/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:66                                                        
  25:     0x5574c8a104ad - <core::pin::Pin<P> as core::future::future::Future>::poll::h6aa9c7207adebc07                                                                                                     
                               at /home/michael/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/future.rs:118                                                    
  26:     0x5574c8a104ad - <F as futures_core::future::TryFuture>::try_poll::h5633e6d6a71350d5                                                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-core-0.3.5/src/future.rs:83                                                                         
  27:     0x5574c8a104ad - <futures_util::future::try_future::into_future::IntoFuture<Fut> as core::future::future::Future>::poll::h20812bb48a44deb6                                                        
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/try_future/into_future.rs:31                                                  
  28:     0x5574c8a104ad - <futures_util::future::future::map::Map<Fut,F> as core::future::future::Future>::poll::h7de76b6b06dabc84                                                                         
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/future/map.rs:67                                                              
  29:     0x5574c8a10298 - <futures_util::future::future::Map<Fut,F> as core::future::future::Future>::poll::h87636451ef52bf16                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  30:     0x5574c8a10298 - <futures_util::future::try_future::MapErr<Fut,F> as core::future::future::Future>::poll::hf361a24bd15b64de                                                                       
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  31:     0x5574c8a10298 - <futures_util::future::either::Either<A,B> as core::future::future::Future>::poll::h3ba6a79df0fece24                                                                             
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/either.rs:65                                                                  
  32:     0x5574c8a10298 - <F as futures_core::future::TryFuture>::try_poll::h5d9826bce7bec57c                                                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-core-0.3.5/src/future.rs:83                                                                         
  33:     0x5574c8a10298 - <futures_util::future::try_future::into_future::IntoFuture<Fut> as core::future::future::Future>::poll::h8cc4e2435674ca81                                                        
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/try_future/into_future.rs:31                                                  
  34:     0x5574c8a10298 - <futures_util::future::future::map::Map<Fut,F> as core::future::future::Future>::poll::h3a97595fa35bf6b4                                                                         
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/future/map.rs:67                                                              
  35:     0x5574c8a10645 - <futures_util::future::future::Map<Fut,F> as core::future::future::Future>::poll::h1f03e91c826fb89f                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  36:     0x5574c8a10645 - <futures_util::future::try_future::MapErr<Fut,F> as core::future::future::Future>::poll::hbb30c6370d1ad4dd                                                                       
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  37:     0x5574c8a10645 - <futures_util::future::either::Either<A,B> as core::future::future::Future>::poll::h45a493d70ab6cb16                                                                             
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/either.rs:66                                                                  
  38:     0x5574c8a10645 - <F as futures_core::future::TryFuture>::try_poll::h3218040a42683b8c                                                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-core-0.3.5/src/future.rs:83                                                                         
  39:     0x5574c8a10645 - <futures_util::future::try_future::into_future::IntoFuture<Fut> as core::future::future::Future>::poll::hffacf042cca96add                                                        
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/try_future/into_future.rs:31                                                  
  40:     0x5574c8a10645 - <futures_util::future::future::map::Map<Fut,F> as core::future::future::Future>::poll::hd3999158d5641280                                                                         
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/future/map.rs:67                                                              
  41:     0x5574c8a0fca0 - <futures_util::future::future::Map<Fut,F> as core::future::future::Future>::poll::he914f5b3eab7d7ff                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  42:     0x5574c8a0fca0 - <futures_util::future::try_future::MapErr<Fut,F> as core::future::future::Future>::poll::haa236b3c8a953e0b                                                                       
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  43:     0x5574c8a0fca0 - <futures_util::future::either::Either<A,B> as core::future::future::Future>::poll::h79e46a6c42aa3fc0                                                                             
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/either.rs:66                                                                  
  44:     0x5574c8a0fca0 - <F as futures_core::future::TryFuture>::try_poll::h11442ab0450f9aba                                                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-core-0.3.5/src/future.rs:83                                                                         
  45:     0x5574c8a0fca0 - <futures_util::future::try_future::into_future::IntoFuture<Fut> as core::future::future::Future>::poll::h4514bbaa544f1a54                                                        
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/try_future/into_future.rs:31                                                  
  46:     0x5574c8a0fca0 - <futures_util::future::future::map::Map<Fut,F> as core::future::future::Future>::poll::h3467a48e5d1b449e                                                                         
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/future/future/map.rs:67                                                              
  47:     0x5574c8a0f5e5 - <futures_util::future::future::Map<Fut,F> as core::future::future::Future>::poll::hc132b12a66e846ba                                                                              
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107                                                                           
  48:     0x5574c8a0f5e5 - <futures_util::future::try_future::MapErr<Fut,F> as core::future::future::Future>::poll::hbbbc3932986b69ae                                                                       
                               at /home/michael/.cargo/registry/src/github.com-1ecc6299db9ec823/futures-util-0.3.5/src/lib.rs:107

Answer 1

My guess is that the task is jumping around to different cores and their clocks are not in lockstep, thus causing the non-monotonicity.

elapsed() just calculates now() - *self So instead of checking elapsed() > period check if now() > delta + period

Answer 2

Your code is completely correct. You should submit a bug to https://github.com/rust-lang/rust. Windows and ARM Linux already have workarounds for similar issues.