venator-engine-0.4.1/src/index/span_indexes.rs:177:31: index out of bounds: the len is 0 but the index is 0

[xmo-odoo]

The full trace is

thread '<unnamed>' panicked at venator-engine-0.4.1/src/index/span_indexes.rs:177:31:
index out of bounds: the len is 0 but the index is 0
stack backtrace:
   0:     0x5d8c9f8e13da - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::he089f96442833f67
   1:     0x5d8c9f90e163 - core::fmt::write::h2f210ed4c94745cb
   2:     0x5d8c9f8dd353 - std::io::Write::write_fmt::h7de08171ab770fb2
   3:     0x5d8c9f8e1222 - std::sys::backtrace::BacktraceLock::print::h810fbd31421329e6
   4:     0x5d8c9f8e2450 - std::panicking::default_hook::{{closure}}::hbaad47ed9dc6356d
   5:     0x5d8c9f8e2230 - std::panicking::default_hook::h24e207139139d40a
   6:     0x5d8c9f8e2bb2 - std::panicking::rust_panic_with_hook::ha9131beeb2ddc506
   7:     0x5d8c9f8e295a - std::panicking::begin_panic_handler::{{closure}}::h1bba0eaeb6da506f
   8:     0x5d8c9f8e18d9 - std::sys::backtrace::__rust_end_short_backtrace::h1d1ca3eade483f4c
   9:     0x5d8c9f8e25ed - rust_begin_unwind
  10:     0x5d8c9eddcb90 - core::panicking::panic_fmt::h896a0727a1a943f9
  11:     0x5d8c9eddcd72 - core::panicking::panic_bounds_check::hc5c09b1b32c09393
  12:     0x5d8c9f49f6b2 - venator_engine::index::span_indexes::SpanIndexes::update_with_closed::h8c56d99939cce4d9
  13:     0x5d8c9f1ca04f - venator_engine::engine::sync_engine::SyncEngine<S>::insert_span_event::h2c290a3189f413ec
  14:     0x5d8c9f1080a4 - std::sys::backtrace::__rust_begin_short_backtrace::h5363600beb3b1933
  15:     0x5d8c9f1ea5fc - core::ops::function::FnOnce::call_once{{vtable.shim}}::hd56a485232b3df10
  16:     0x5d8c9f8e8e3b - std::sys::pal::unix::thread::Thread::new::thread_start::ha07e360225fa3528
  17:     0x77f220894ac3 - start_thread
                               at ./nptl/pthread_create.c:442:8
  18:     0x77f220926850 - __GI___clone3
                               at ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
  19:                0x0 - <unknown>

It looks like this happens because I have filtered spans list(s) open during ingestion: once the event producers stop the panic spam stops, and if I restart the event producers the panics resume.

[kmdreko]

I see the flow that could reach that panic but I'm unsure exactly what could cause it. The symptoms indicate receiving a span close event for an already-closed span. Having a filtered view open should not affect ingest in any way.

I'll update the code to handle that case more gracefully regardless.