fix: drastically reduce time taken to check for cycles (#2874)

lerna · Jun 14, 2022 · 4b81a98 · 4b81a98
1 parent f2ece94
commit 4b81a98
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/core/package-graph/index.js b/core/package-graph/index.js
@@ -218,6 +218,9 @@ class PackageGraph extends Map {
     /** @type {(PackageGraphNode | CyclicPackageGraphNode)[]} */
     const walkStack = [];
 
+    /** @type {Set<PackageGraphNode>} */
+    const alreadyVisited = new Set();
+
     function visits(baseNode, dependentNode) {
       if (nodeToCycle.has(baseNode)) {
         return;
@@ -228,6 +231,12 @@ class PackageGraph extends Map {
         topLevelDependent = nodeToCycle.get(topLevelDependent);
       }
 
+      // Otherwise the same node is checked multiple times which is very wasteful in a large repository
+      if (alreadyVisited.has(topLevelDependent)) {
+        return;
+      }
+      alreadyVisited.add(topLevelDependent);
+
       if (
         topLevelDependent === baseNode ||
         (topLevelDependent.isCycle && topLevelDependent.has(baseNode.name))