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https://issues.apache.org/jira/browse/FLINK-34655?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17825669#comment-17825669
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Rui Fan commented on FLINK-34655:
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{quote}But the vertex parallelism overrides feature was introduced in 1.17 so
the autoscaler never really officially supported anything before that{quote}
We(our internal platform) want to use the autoscaler to give some parallelism
setting suggestions to our users. We suggest they upgrade job to 1.17 or later
version if users want to scaling automatically.
And that's why we want to parse scaling report. In the short term, we only use
the autoscaler to give suggestion instead of scaling directly. After our users
think the parallelism calculation is reliable, they will have stronger
motivation to upgrade the flink version.
> Autoscaler doesn't work for flink 1.15
> --------------------------------------
>
> Key: FLINK-34655
> URL: https://issues.apache.org/jira/browse/FLINK-34655
> Project: Flink
> Issue Type: Bug
> Components: Autoscaler
> Reporter: Rui Fan
> Assignee: Rui Fan
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.8.0
>
>
> flink-ubernetes-operator is committed to supporting the latest 4 flink minor
> versions, and autoscaler is a part of flink-ubernetes-operator. Currently,
> the latest 4 flink minor versions are 1.15, 1.16, 1.17 and 1.18.
> But autoscaler doesn't work for flink 1.15.
> h2. Root cause:
> * FLINK-28310 added some properties in IOMetricsInfo in flink-1.16
> * IOMetricsInfo is a part of JobDetailsInfo
> * JobDetailsInfo is necessary for autoscaler [1]
> * flink's RestClient doesn't allow miss any property during deserializing the
> json
> That means that the RestClient after 1.15 cannot fetch JobDetailsInfo for
> 1.15 jobs.
> h2. How to fix it properly?
> Flink side support ignore unknown properties.
> FLINK-33268 already do it. But I try run autoscaler with flink-1.15 job, it
> still doesn't work. Because the IOMetricsInfo added some properties, they are
> primitive type.
> It should disable DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES as well.
> (Not sure whether it should be a seperate FLIP or it can be a part of
> FLIP-401 [2].)
> h2. How to fix it in the short term?
> 1. Copy the latest RestMapperUtils and RestClient from master branch (It
> includes FLINK-33268) to flink-autoscaler module. (The copied class will be
> loaded first)
> 2. Disable DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES in
> RestMapperUtils#flexibleObjectMapper in copied class.
> Based on these 2 steps, flink-1.15 works well with autoscaler. (I try it
> locally).
> After DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES in
> RestMapperUtils#flexibleObjectMapper is disabled, and the corresponding code
> is released in flink side. flink-ubernetes-operator can remove these 2 copied
> classes.
> [1]
> https://github.com/apache/flink-kubernetes-operator/blob/ede1a610b3375d31a2e82287eec67ace70c4c8df/flink-autoscaler/src/main/java/org/apache/flink/autoscaler/ScalingMetricCollector.java#L109
> [2]
> https://cwiki.apache.org/confluence/display/FLINK/FLIP-401%3A+REST+API+JSON+response+deserialization+unknown+field+tolerance
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