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Turbopack: add traces to merged module computation #83908

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Merged
merged 3 commits into from
Sep 17, 2025
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Turbopack: add traces to merged module computation #83908

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24 changes: 17 additions & 7 deletions turbopack/crates/turbopack-core/src/module_graph/merged_modules.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,9 +3,7 @@ use std::collections::hash_map::Entry;
use anyhow::{Context, Result, bail};
use rustc_hash::{FxHashMap, FxHashSet};
use tracing::Instrument;
use turbo_tasks::{
FxIndexMap, FxIndexSet, ResolvedVc, TryFlatJoinIterExt, TryJoinIterExt, ValueToString, Vc,
};
use turbo_tasks::{FxIndexMap, FxIndexSet, ResolvedVc, TryFlatJoinIterExt, TryJoinIterExt, Vc};

use crate::{
chunk::{
Expand Down Expand Up @@ -99,6 +97,7 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
let mut entry_modules =
FxHashSet::with_capacity_and_hasher(module_count, Default::default());

let inner_span = tracing::info_span!("collect mergeable modules");
let mergeable = graphs
.iter()
.flat_map(|g| g.iter_nodes())
Expand All @@ -113,10 +112,13 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
Ok(None)
})
.try_flat_join()
.instrument(inner_span)
.await?
.into_iter()
.collect::<FxHashSet<_>>();

let inner_span = tracing::info_span!("fixed point traversal").entered();

let mut next_index = 0u32;
let visit_count = module_graph.traverse_edges_fixed_point_with_priority(
entries.iter().map(|e| (*e, 0)),
Expand Down Expand Up @@ -197,6 +199,9 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
|_, _| Ok(0),
)?;

drop(inner_span);
let inner_span = tracing::info_span!("chunk group collection").entered();

span.record("visit_count", visit_count);

#[derive(Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
Expand Down Expand Up @@ -313,6 +318,9 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
)?;
}

drop(inner_span);
let inner_span = tracing::info_span!("exposed computation").entered();

// We use list.pop() below, so reverse order using negation
lists_reverse_indices
.sort_by_cached_key(|_, b| b.iter().map(|o| o.entry).min().map(|v| -(v as i64)));
Expand Down Expand Up @@ -363,6 +371,8 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
},
)?;

drop(inner_span);
let inner_span = tracing::info_span!("reconciliation").entered();
while let Some((_, common_occurrences)) = lists_reverse_indices.pop() {
if common_occurrences.len() < 2 {
// Module exists only in one list, no need to split
Expand Down Expand Up @@ -485,10 +495,7 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
lists.push(after_list.clone());
for (i, &m) in after_list.iter().enumerate() {
let Some(occurrences) = lists_reverse_indices.get_mut(&m) else {
bail!(
"Couldn't find module in list {:?}",
m.ident().to_string().await?,
);
bail!("Couldn't find module in reverse list");
};

let removed = occurrences.swap_remove(&ListOccurrence {
Expand All @@ -509,6 +516,8 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
// Dedupe the lists
let lists = lists.into_iter().collect::<FxHashSet<_>>();

drop(inner_span);
let inner_span = tracing::info_span!("merging");
// Call MergeableModule impl to merge the modules.
let result = lists
.into_iter()
Expand Down Expand Up @@ -570,6 +579,7 @@ pub async fn compute_merged_modules(module_graph: Vc<ModuleGraph>) -> Result<Vc<
)))
})
.try_join()
.instrument(inner_span)
.await?;

#[allow(clippy::type_complexity)]
Expand Down
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