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Posted to issues@flink.apache.org by "Zhu Zhu (Jira)" <ji...@apache.org> on 2025/12/10 07:07:00 UTC

[jira] [Closed] (FLINK-38754) An unnecessary reverse DNS lookup when TaskManager connects to BlobServer

     [ https://issues.apache.org/jira/browse/FLINK-38754?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Zhu Zhu closed FLINK-38754.
---------------------------
    Resolution: Fixed

7ba97419d200adef672b67c52c2b5a79f277cfda

> An unnecessary reverse DNS lookup when TaskManager connects to BlobServer
> -------------------------------------------------------------------------
>
>                 Key: FLINK-38754
>                 URL: https://issues.apache.org/jira/browse/FLINK-38754
>             Project: Flink
>          Issue Type: Improvement
>          Components: Runtime / Coordination
>            Reporter: Yi Zhang
>            Assignee: Yi Zhang
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 2.3.0
>
>
> An unnecessary reverse DNS lookup occurs when creating a BlobClient. Specifically, during the connection establishment between BlobClient and BlobServer, the code invokes `InetSocketAddress#getHostName()` and subsequently recreates the `InetSocketAddress`.
> I understand this behavior was introduced as part of the fix for FLINK-10213 to add retry logic in case of initial DNS resolution failures. However, in real-world production environments, when a TaskManager establishes a connection with the ResourceManager, it may get an IP address string directly (e.g., when no DNS service is available or to minimize DNS-related overhead). In such cases, calling getHostName() triggers an unnecessary reverse DNS lookup, which can introduce latency and potential failure points.
> Maybe it's better to change the implementation to use `InetSocketAddress#getHostString()` instead, which returns the original hostname or IP address string without performing any reverse DNS resolution. This would avoid the redundant lookup while preserving the intended retry logic for actual hostnames.



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