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Make server panic hook more error resilient - #12610
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Aug 1, 2024
| // This communicates that this isn't a linter error but ruff itself hard-errored for | ||
| // some reason (e.g. failed to resolve the configuration) | ||
| eprintln!("{}", "ruff failed".red().bold()); | ||
| writeln!(stderr, "{}", "ruff failed".red().bold()).ok(); |
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Looking at the original trace, I strongly suspect that ruff panics here... when trying to print the reason why ruff errored:
failed printing to stderr: Broken pipe (os error 32)
0: ruff_server::message::init_messenger::{{closure}}
1: std::panicking::rust_panic_with_hook
2: std::panicking::begin_panic_handler::{{closure}}
3: std::sys_common::backtrace::__rust_end_short_backtrace
4: rust_begin_unwind
5: core::panicking::panic_fmt
6: std::io::stdio::_eprint
7: ruff::main
8: std::sys_common::backtrace::__rust_begin_short_backtrace
9: std::rt::lang_start::{{closure}}
10: std::rt::lang_start_internal
11: main
12: <unknown>
13: __libc_start_main
14: <unknown>
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MichaReiser
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Aug 2, 2024
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| let mut stderr = std::io::stderr().lock(); | ||
| writeln!(stderr, "{panic_info}\n{backtrace}").ok(); |
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The main change is to use writeln here
MichaReiser
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Aug 2, 2024
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| // unregister any previously registered panic hook | ||
| let _ = std::panic::take_hook(); | ||
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| // When we panic, try to notify the client. | ||
| std::panic::set_hook(Box::new(move |panic_info| { | ||
| if let Some(messenger) = MESSENGER.get() { | ||
| let _ = messenger.send(lsp_server::Message::Notification( | ||
| lsp_server::Notification { | ||
| method: lsp_types::notification::ShowMessage::METHOD.into(), | ||
| params: serde_json::to_value(lsp_types::ShowMessageParams { | ||
| typ: lsp_types::MessageType::ERROR, | ||
| message: String::from( | ||
| "The Ruff language server exited with a panic. See the logs for more details." | ||
| ), | ||
| }) | ||
| .unwrap_or_default(), | ||
| }, | ||
| )); | ||
| } | ||
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| let backtrace = std::backtrace::Backtrace::force_capture(); | ||
| tracing::error!("{panic_info}\n{backtrace}"); | ||
| #[allow(clippy::print_stderr)] | ||
| { | ||
| // we also need to print to stderr directly in case tracing hasn't | ||
| // been initialized. | ||
| eprintln!("{panic_info}\n{backtrace}"); | ||
| } | ||
| })); |
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I decided to move this out of Messenger to ensure that we unset the panic hook when the server shuts down. We may consider using catch_unwind on a per request/response model in the future. But I think that's good enough for now
dhruvmanila
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Aug 2, 2024
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This seems reasonable although I've never faced this panic.
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Summary
eprintlncan panic when the stderr pipe is broken which is very unfortunate if it happens in the server's panic hook.This PR uses
writelnwith.ok()as a more forgiving way to write the error message.This should fix #12545 although it is still unclear to me how to get into the broken pipe case.
Test Plan
I added a panic in the diagnostics request: