tracing: add an example of tracing in a panic hook
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It turns out that when using the global dispatcher, emitting tracing events in a panic hook will capture the span in which the program panicked. This is very handy for debugging panics! Thanks a lot to @nate_mara for pointing this out to me on twitter --- I hadn't even thought of it! Since it isn't necessarily immediately obvious that this works, I thought it would be nice to add an example.
LucioFranco
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Apr 28, 2021
| // If we are currently in a span when the panic occurred, the logged event | ||
| // will include the current span, allowing the context in which the panic | ||
| // occurred to be recorded. | ||
| std::panic::set_hook(Box::new(|panic| { |
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Can we make this built-in?
tracing::set_panic_hook()
and could fail if no global one is set?
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yes, might be worth a follow-up change to add something like that.
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I'd suggest opening an issue to centralize discussion: https://github.com/tokio-rs/tracing/issues/new?assignees=&labels=&template=feature_request.md.
However, I'm personally not inclined to have this in tracing for the following reasons:
- Users might want to handle panics in different ways, with different formatting, levels, and so forth. They might not want to involve tracing in the first place!
- Other users might not want
tracingto change their panic hooks or they might wanttracingand some other functionality in their panic hooks. If the data passed to the panic hook is paramaterized, then I'm not sure what the benefit of atracing-vended panic hook is overstd:panic::set_hook. - Failing/panicking if
tracing::set_panic_hook(or another panic hook) is way too opinionated fortracing, IMO.
hawkw
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Apr 30, 2021
It turns out that when using the global dispatcher, emitting tracing events in a panic hook will capture the span in which the program panicked. This is very handy for debugging panics! Thanks a lot to @nate_mara for pointing this out to me on twitter --- I hadn't even thought of it! Since it isn't necessarily immediately obvious that this works, I thought it would be nice to add an example.
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hawkw
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Apr 30, 2021
It turns out that when using the global dispatcher, emitting tracing events in a panic hook will capture the span in which the program panicked. This is very handy for debugging panics! Thanks a lot to @nate_mara for pointing this out to me on twitter --- I hadn't even thought of it! Since it isn't necessarily immediately obvious that this works, I thought it would be nice to add an example.
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It turns out that when using the global dispatcher, emitting tracing
events in a panic hook will capture the span in which the program
panicked. This is very handy for debugging panics! Thanks a lot to
@natemara for pointing this out to me on twitter --- I hadn't even
thought of it!
Since it isn't necessarily immediately obvious that this works, I
thought it would be nice to add an example.