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ASF GitHub Bot commented on GEARPUMP-349: ----------------------------------------- Github user manuzhang commented on a diff in the pull request: https://github.com/apache/incubator-gearpump/pull/223#discussion_r138879455 --- 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)]] + private val _inEdges = mutable.Map.empty[N, List[(N, E, N)]] --- End diff -- Why do we have "_abc" style variable names here ? > Graph#topologicalOrderIterator is slow for large graph > ------------------------------------------------------ > > Key: GEARPUMP-349 > URL: https://issues.apache.org/jira/browse/GEARPUMP-349 > Project: Apache Gearpump > Issue Type: Improvement > Components: core > Affects Versions: 0.8.4 > Reporter: Manu Zhang > Assignee: Huafeng Wang > Fix For: 0.8.5 > > > The algorithm is as follows > 1. find zero in-degree nodes from a copied graph. > 2. remove nodes from the copied graph and add them to the output > 3. repeat 1 > The issue is that step 1 traverses all remaining nodes each time, which costs > the algorithm {{O(n^2)}} time > {{Graph#hasCycle}} has a similar issue -- This message was sent by Atlassian JIRA (v6.4.14#64029)