[red-knot] Improve symbol-lookup tracing #14907

sharkdp · 2024-12-11T08:41:18Z

Summary

When debugging, I frequently want to know which symbols are being looked up. symbol_by_id adds tracing information, but it only shows the ScopedSymbolId. Since symbol_by_id is only called from symbol, it seems reasonable to move the tracing call one level up from symbol_by_id to symbol, where we can also show the name of the symbol.

Before:

6      └─┐red_knot_python_semantic::types::infer::infer_expression_types{expression=Id(60de), file=/home/shark/tomllib_modified/_parser.py}
6        └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(33)}
6        ┌─┘
6        └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(123)}
6        ┌─┘
6        └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(54)}
6        ┌─┘
6        └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(122)}
6        ┌─┘
6        └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(165)}
6        ┌─┘
6      ┌─┘
6      └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(32)}
6      ┌─┘
6      └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(232)}
6      ┌─┘
6    ┌─┘
6  ┌─┘
6┌─┘

After:

5      └─┐red_knot_python_semantic::types::infer::infer_expression_types{expression=Id(60de), file=/home/shark/tomllib_modified/_parser.py}
5        └─┐red_knot_python_semantic::types::symbol{name="dict"}
5        ┌─┘
5        └─┐red_knot_python_semantic::types::symbol{name="dict"}
5        ┌─┘
5        └─┐red_knot_python_semantic::types::symbol{name="list"}
5        ┌─┘
5        └─┐red_knot_python_semantic::types::symbol{name="list"}
5        ┌─┘
5        └─┐red_knot_python_semantic::types::symbol{name="isinstance"}
5        ┌─┘
5        └─┐red_knot_python_semantic::types::symbol{name="isinstance"}
5        ┌─┘
5      ┌─┘
5      └─┐red_knot_python_semantic::types::symbol{name="ValueError"}
5      ┌─┘
5      └─┐red_knot_python_semantic::types::symbol{name="ValueError"}
5      ┌─┘
5    ┌─┘
5  ┌─┘
5┌─┘

Test Plan

cargo run --bin red_knot -- --current-directory path/to/tomllib -vvv

MichaReiser · 2024-12-11T08:44:41Z

crates/red_knot_python_semantic/src/types.rs


 /// Infer the public type of a symbol (its type as seen from outside its scope).
 fn symbol_by_id<'db>(db: &'db dyn Db, scope: ScopeId<'db>, symbol: ScopedSymbolId) -> Symbol<'db> {
-    let _span = tracing::trace_span!("symbol_by_id", ?symbol).entered();


I'm inclined to inline the entire symbol_by_id function into symbol to avoid "missing" symbol lookups in tracing because a symbol gets looked up by its id.

symbol_by_id is now #[salsa::tracked], so I can't inline it trivially. Also, it feels a bit wrong to inline that nicely encapsulated into this lambda here:

ruff/crates/red_knot_python_semantic/src/types.rs

Lines 171 to 175 in 897c307

let table = symbol_table(db, scope);

table

.symbol_id_by_name(name)

.map(|symbol| symbol_by_id(db, scope, symbol))

.unwrap_or(Symbol::Unbound)

I now pushed a version where I nested symbol_by_id inside symbol. I'm not a huge fan, but it solves your concern as well. What do you think @MichaReiser?

(The diff is horrible. The only thing I did was to move symbol_by_id inside symbol and adapted the doc comments. No code has been changed except for the removed/added tracing::trace_span line.

(The diff is horrible. The only thing I did was to move symbol_by_id inside symbol and adapted the doc comments. No code has been changed except for the removed/added tracing::trace_span line.

fyi if you click the gear icon at the top of the diff view, you can check "Hide whitespace", which makes this particular diff much cleaner

Thanks! I know about hide-whitespace, but somehow didn't think of enabling it for this changeset 👍

github-actions · 2024-12-11T08:47:27Z

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AlexWaygood

I agree with Micha's comment, but LGTM otherwise. (Wow, that output is so much more useful!)

carljm

So much better, thank you!

When debugging, I frequently want to know which symbols are be looked up. `symbol_by_id` adds tracing information, but it only shows the `ScopedSymbolId`. Since `symbol_by_id` is only called from `symbol`, it seems reasonable to move the tracing call to `symbol` where we can also show the name of the symbol. **Before**: ``` 6 └─┐red_knot_python_semantic::types::infer::infer_expression_types{expression=Id(60de), file=/home/shark/tomllib_modified/_parser.py} 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(33)} 6 ┌─┘ 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(123)} 6 ┌─┘ 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(54)} 6 ┌─┘ 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(122)} 6 ┌─┘ 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(165)} 6 ┌─┘ 6 ┌─┘ 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(32)} 6 ┌─┘ 6 └─┐red_knot_python_semantic::types::symbol_by_id{symbol=ScopedSymbolId(232)} 6 ┌─┘ 6 ┌─┘ 6 ┌─┘ 6┌─┘ ``` **After**: ``` 5 └─┐red_knot_python_semantic::types::infer::infer_expression_types{expression=Id(60de), file=/home/shark/tomllib_modified/_parser.py} 5 └─┐red_knot_python_semantic::types::symbol{name="dict"} 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="dict"} 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="list"} 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="list"} 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="isinstance"} 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="isinstance"} 5 ┌─┘ 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="ValueError"} 5 ┌─┘ 5 └─┐red_knot_python_semantic::types::symbol{name="ValueError"} 5 ┌─┘ 5 ┌─┘ 5 ┌─┘ 5┌─┘ ```

sharkdp · 2025-01-07T09:35:20Z

crates/red_knot_python_semantic/src/types.rs

+    #[salsa::tracked]
+    fn symbol_by_id<'db>(
+        db: &'db dyn Db,
+        scope: ScopeId<'db>,


I tried to remove this (and use scope from the outer scope), but it seems to be required in order to make this salsa_tracked.

This works for me. Thanks

* main: Use uv consistently throughout the documentation (#15302) [red-knot] Eagerly normalize `type[]` types (#15272) [`pyupgrade`] Split `UP007` to two individual rules for `Union` and `Optional` (`UP007`, `UP045`) (#15313) [red-knot] Improve symbol-lookup tracing (#14907) [red-knot] improve type shrinking coverage in red-knot property tests (#15297) [`flake8-return`] Recognize functions returning `Never` as non-returning (`RET503`) (#15298) [`flake8-bugbear`] Implement `class-as-data-structure` (`B903`) (#9601) Avoid treating newline-separated sections as sub-sections (#15311) Remove call when removing final argument from `format` (#15309) Don't enforce `object-without-hash-method` in stubs (#15310) Don't special-case class instances in binary expression inference (#15161) Upgrade zizmor to the latest version in CI (#15300)

sharkdp added the ty Multi-file analysis & type inference label Dec 11, 2024

sharkdp requested review from AlexWaygood, MichaReiser and carljm as code owners December 11, 2024 08:41

MichaReiser approved these changes Dec 11, 2024

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AlexWaygood approved these changes Dec 11, 2024

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carljm approved these changes Dec 11, 2024

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sharkdp force-pushed the david/tracing-symbol-lookups branch from c16c17e to 5529405 Compare January 7, 2025 09:25

sharkdp force-pushed the david/tracing-symbol-lookups branch from 5529405 to 897c307 Compare January 7, 2025 09:30

sharkdp commented Jan 7, 2025

View reviewed changes

sharkdp merged commit ce9c496 into main Jan 7, 2025
21 checks passed

sharkdp deleted the david/tracing-symbol-lookups branch January 7, 2025 09:41

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	let table = symbol_table(db, scope);
	table
	.symbol_id_by_name(name)
	.map(\|symbol\| symbol_by_id(db, scope, symbol))
	.unwrap_or(Symbol::Unbound)

[red-knot] Improve symbol-lookup tracing #14907

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