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https://issues.apache.org/jira/browse/GEARPUMP-349?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16166177#comment-16166177
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ASF GitHub Bot commented on GEARPUMP-349:
-----------------------------------------
Github user manuzhang commented on the issue:
https://github.com/apache/incubator-gearpump/pull/223
We also do an extra check for cycle here. Can it be removed ?
```scala
if (dag.hasCycle()) {
LOG.warn(s"Detected cycles in DAG of application $name!")
}
val indices =
dag.topologicalOrderWithCirclesIterator.toList.zipWithIndex.toMap
```
> 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
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