Github user manuzhang commented on a diff in the pull request:
https://github.com/apache/incubator-gearpump/pull/223#discussion_r138875439
--- Diff: core/src/main/scala/org/apache/gearpump/util/Graph.scala ---
@@ -28,6 +29,8 @@ class Graph[N, E](vertexList: List[N], edgeList: List[(N,
E, N)]) extends Serial
private val _vertices = mutable.Set.empty[N]
private val _edges = mutable.Set.empty[(N, E, N)]
+ private val _outEdges = mutable.Map.empty[N, List[(N, E, N)]]
--- End diff --
Will `Set` perform better than `List` here ?
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