fix: out-of-memory error during peers resolution (#7149)

.changeset/olive-apricots-change.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/resolve-dependencies": patch
+"pnpm": patch
+---
+
+Optimize peers resolution to avoid out-of-memory exceptions in some rare cases, when there are too many circular dependencies and peer dependencies [#7149](https://github.com/pnpm/pnpm/pull/7149).

pkg-manager/resolve-dependencies/src/resolvePeers.ts

@@ -9,6 +9,7 @@ import type {
 } from '@pnpm/types'
 import { depPathToFilename, createPeersFolderSuffix } from '@pnpm/dependency-path'
 import mapValues from 'ramda/src/map'
+import partition from 'ramda/src/partition'
 import pick from 'ramda/src/pick'
 import scan from 'ramda/src/scan'
 import {
@@ -497,7 +498,12 @@ function resolvePeersOfChildren<T extends PartialResolvedPackage> (
   const allResolvedPeers = new Map<string, string>()
   const allMissingPeers = new Set<string>()
 
-  for (const childNodeId of Object.values(children)) {
+  // Partition children based on whether they're repeated in parentPkgs.
+  // This impacts the efficiency of graph traversal and prevents potential out-of-memory errors.mes can even lead to out-of-memory exceptions.
+  const [repeated, notRepeated] = partition(([alias]) => parentPkgs[alias] != null, Object.entries(children))
+
+  // Resolving non-repeated nodes before repeated nodes proved to be slightly faster.
+  for (const [, childNodeId] of [...notRepeated, ...repeated]) {
     const { resolvedPeers, missingPeers } = resolvePeersOfNode(childNodeId, parentPkgs, ctx)
     for (const [k, v] of resolvedPeers) {
       allResolvedPeers.set(k, v)