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JoinHandle::abort() panics with "scheduler context missing" when using basic scheduler #3662

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gh2o opened this issue Mar 30, 2021 · 4 comments · Fixed by #3672
Closed

JoinHandle::abort() panics with "scheduler context missing" when using basic scheduler #3662

gh2o opened this issue Mar 30, 2021 · 4 comments · Fixed by #3672
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@udoprog
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A-tokio Area: The main tokio crate C-bug Category: This is a bug. M-task Module: tokio/task

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@gh2o
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gh2o commented Mar 30, 2021 •
edited
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Version
tokio v1.4.0
tokio-macros v1.1.0 (proc-macro)

Platform
Linux mtgav 5.10.4-arch2-1 #1 SMP PREEMPT Fri, 01 Jan 2021 05:29:53 +0000 x86_64 GNU/Linux

Description
When using the basic scheduler/current_thread, JoinHandle::abort() panics if called from a spawn_blocking thread. Same bug as #3157 but with the basic scheduler or flavor = "current_thread". It can be worked around by doing the abort within a tokio::spawn(), but if this limitation is intentional it should be added the documentation.

Code snippet:

use std::time::Duration;

#[tokio::main(flavor = "current_thread")]
async fn main() {
    let j = tokio::spawn(tokio::time::sleep(Duration::from_secs(3)));
    let _ = tokio::task::spawn_blocking(move || {
        std::thread::sleep(Duration::from_secs(1));
        j.abort();
    }).await;
}

Resulting panic:

thread 'tokio-runtime-worker' panicked at 'scheduler context missing', /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/basic_scheduler.rs:376:31
stack backtrace:
   0: rust_begin_unwind
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:495:5
   1: core::panicking::panic_fmt
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/panicking.rs:92:14
   2: core::option::expect_failed
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/option.rs:1260:5
   3: core::option::Option<T>::expect
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/core/src/option.rs:349:21
   4: tokio::runtime::basic_scheduler::<impl tokio::runtime::task::Schedule for alloc::sync::Arc<tokio::runtime::basic_scheduler::Shared>>::release::{{closure}}
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/basic_scheduler.rs:376:22
   5: tokio::macros::scoped_tls::ScopedKey<T>::with
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/macros/scoped_tls.rs:72:13
   6: tokio::runtime::basic_scheduler::<impl tokio::runtime::task::Schedule for alloc::sync::Arc<tokio::runtime::basic_scheduler::Shared>>::release
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/basic_scheduler.rs:375:9
   7: tokio::runtime::task::core::Scheduler<S>::release::{{closure}}
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/core.rs:197:36
   8: tokio::loom::std::unsafe_cell::UnsafeCell<T>::with
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/loom/std/unsafe_cell.rs:10:9
   9: tokio::runtime::task::core::Scheduler<S>::release
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/core.rs:193:9
  10: tokio::runtime::task::harness::SchedulerView<S>::transition_to_terminal
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:221:33
  11: tokio::runtime::task::harness::Harness<T,S>::complete
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:186:12
  12: tokio::runtime::task::harness::Harness<T,S>::shutdown
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:164:9
  13: tokio::runtime::task::raw::shutdown
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/raw.rs:130:5
  14: tokio::runtime::task::raw::RawTask::shutdown
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/raw.rs:90:18
  15: tokio::runtime::task::join::JoinHandle<T>::abort
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/join.rs:195:13
  16: joinhandle_abort::main::{{closure}}::{{closure}}
             at ./src/main.rs:8:9
  17: <tokio::runtime::blocking::task::BlockingTask<T> as core::future::future::Future>::poll
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/blocking/task.rs:42:21
  18: tokio::runtime::task::core::CoreStage<T>::poll::{{closure}}
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/core.rs:235:17
  19: tokio::loom::std::unsafe_cell::UnsafeCell<T>::with_mut
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/loom/std/unsafe_cell.rs:14:9
  20: tokio::runtime::task::core::CoreStage<T>::poll
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/core.rs:225:13
  21: tokio::runtime::task::harness::poll_future::{{closure}}
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:422:23
  22: <std::panic::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panic.rs:322:9
  23: std::panicking::try::do_call
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:381:40
  24: __rust_try
  25: std::panicking::try
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panicking.rs:345:19
  26: std::panic::catch_unwind
             at /rustc/e1884a8e3c3e813aada8254edfa120e85bf5ffca/library/std/src/panic.rs:396:14
  27: tokio::runtime::task::harness::poll_future
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:409:19
  28: tokio::runtime::task::harness::Harness<T,S>::poll_inner
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:89:9
  29: tokio::runtime::task::harness::Harness<T,S>::poll
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/harness.rs:59:15
  30: tokio::runtime::task::raw::poll
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/raw.rs:104:5
  31: tokio::runtime::task::raw::RawTask::poll
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/raw.rs:66:18
  32: tokio::runtime::task::Notified<S>::run
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/task/mod.rs:171:9
  33: tokio::runtime::blocking::pool::Inner::run
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/blocking/pool.rs:278:17
  34: tokio::runtime::blocking::pool::Spawner::spawn_thread::{{closure}}
             at /home/gavin/.cargo/registry/src/github.com-1ecc6299db9ec823/tokio-1.4.0/src/runtime/blocking/pool.rs:258:17
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
@gh2o gh2o added A-tokio Area: The main tokio crate C-bug Category: This is a bug. labels Mar 30, 2021
@Darksonn Darksonn added the M-task Module: tokio/task label Mar 30, 2021
@Darksonn
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No, this isn't intentional. Does it also fail if called from std::thread::spawn?

@gh2o
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gh2o commented Mar 30, 2021 •
edited
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Yes, that crashes as well:

use std::time::Duration;

#[tokio::main(flavor = "current_thread")]
async fn main() {
    let j = tokio::spawn(tokio::time::sleep(Duration::from_secs(3)));
    let t = std::thread::spawn(move || {
        std::thread::sleep(Duration::from_secs(1));
        j.abort();
    });
    tokio::time::sleep(Duration::from_secs(2)).await;
    assert!(t.join().is_err());
}

udoprog added a commit to udoprog/tokio that referenced this issue Apr 4, 2021
@udoprog
Prevent basic scheduler panic on task release (fixes tokio-rs#3662)
c6221e8
@udoprog udoprog mentioned this issue Apr 4, 2021
Merged
@davidpdrsn davidpdrsn linked a pull request Apr 6, 2021 that will close this issue
Prevent basic_scheduler from panicking if a task is aborted from another thread #3672
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@carllerche
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Hey, would you be able to check if #3672 fixes your issue?

@gh2o
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gh2o commented Apr 8, 2021

@carllerche @udoprog Yes, it looks like it's fixed now. Thanks y'all!

carllerche pushed a commit that referenced this issue Apr 8, 2021
@udoprog
rt: fix panic in JoinHandle::abort() when called from other thread (#…
1a72b28 
…3672)

When aborting a task registered with a current-thread scheduler from off runtime, the tasks may not
be immediately unlinked from the runtime. Instead, send a message to the runtime, notifying it to
remove the aborted task.

Fixes #3662
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Prevent basic_scheduler from panicking if a task is aborted from another thread udoprog/tokio
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@carllerche @udoprog @gh2o @Darksonn