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https://issues.apache.org/jira/browse/FLINK-22863?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhu Zhu updated FLINK-22863:
----------------------------
Priority: Blocker (was: Critical)
> ArrayIndexOutOfBoundsException may happen when building rescale edges
> ---------------------------------------------------------------------
>
> Key: FLINK-22863
> URL: https://issues.apache.org/jira/browse/FLINK-22863
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Coordination
> Affects Versions: 1.13.0, 1.13.1
> Reporter: Zhilong Hong
> Priority: Blocker
> Fix For: 1.14.0, 1.13.2
>
> Attachments: image-2021-06-03-15-06-09-301.png
>
>
> For EdgeManagerBuildUtil introduced in FLINK-21326, we find that during the
> construction of rescale edges, it may throw ArrayIndexOutOfBoundsException
> like this:
> !image-2021-06-03-15-06-09-301.png|width=938,height=200!
> It is mainly caused by the precision of {{double}} in Java.
> In EdgeManagerBuildUtil#connectPointwise, when upstream parallelism <
> downstream parallelism, we calculate the indices of downstream vertices that
> connect to each upstream partition like this:
> {code:java}
> int start = (int) (Math.ceil(partitionNum * factor));
> int end = (int) (Math.ceil((partitionNum + 1) * factor));
> {code}
> The index range is [{{start}}, {{end}}).
> In some cases the value of {{end}} may exceed the downstream parallelism and
> throw the ArrayIndexOutOfBoundsException.
> Let's take an example. The upstream parallelism is 7. The downstream
> parallelism is 29. For the last upstream partition (which {{partitionNum}} is
> 6), {{(partitionNum + 1) * factor}} is 29.00002, which is slightly larger
> than 29. This is caused by the precision of {{double}}. Then {{end}} =
> {{Math.ceil(29.00002)}}, which is 30. ArrayIndexOutOfBoundsException is
> thrown here.
> To solve this issue, we need to add an extra check for the boundary condition
> like this:
> {code:java}
> int end = Math.min(targetCount, (int) (Math.ceil((partitionNum + 1) *
> factor)));
> {code}
> This affects release-1.13.0 and release-1.13.1.
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