Enum tokio::runtime::UnhandledPanic

#[non_exhaustive]
pub enum UnhandledPanic {
    Ignore,
    ShutdownRuntime,
}

Available on crate feature rt and tokio_unstable only.

How the runtime should respond to unhandled panics.

Instances of UnhandledPanic are passed to Builder::unhandled_panic to configure the runtime behavior when a spawned task panics.

See Builder::unhandled_panic for more details.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Ignore

The runtime should ignore panics on spawned tasks.

The panic is forwarded to the task’s JoinHandle and all spawned tasks continue running normally.

This is the default behavior.

Examples

use tokio::runtime::{self, UnhandledPanic};

let rt = runtime::Builder::new_current_thread()
    .unhandled_panic(UnhandledPanic::Ignore)
    .build()
    .unwrap();

let task1 = rt.spawn(async { panic!("boom"); });
let task2 = rt.spawn(async {
    // This task completes normally
    "done"
});

rt.block_on(async {
    // The panic on the first task is forwarded to the `JoinHandle`
    assert!(task1.await.is_err());

    // The second task completes normally
    assert!(task2.await.is_ok());
})

ShutdownRuntime

The runtime should immediately shutdown if a spawned task panics.

The runtime will immediately shutdown even if the panicked task’s JoinHandle is still available. All further spawned tasks will be immediately dropped and call to Runtime::block_on will panic.

Examples

use tokio::runtime::{self, UnhandledPanic};

let rt = runtime::Builder::new_current_thread()
    .unhandled_panic(UnhandledPanic::ShutdownRuntime)
    .build()
    .unwrap();

rt.spawn(async { panic!("boom"); });
rt.spawn(async {
    // This task never completes.
});

rt.block_on(async {
    // Do some work
})

Trait Implementations

impl Clone for UnhandledPanic

fn clone(&self) -> UnhandledPanic

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for UnhandledPanic

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.