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[FLINK-40671][network] Document why UnknownInputChannel graduation hardcodes needsRecovery=false #29191

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[FLINK-40671][network] Document why UnknownInputChannel graduation hardcodes needsRecovery=false #29191

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4 changes: 4 additions & 0 deletions ...main/java/org/apache/flink/runtime/io/network/partition/consumer/UnknownInputChannel.java
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Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,8 @@ public RemoteInputChannel toRemoteInputChannel(
metrics.getNumBytesInRemoteCounter(),
metrics.getNumBuffersInRemoteCounter(),
channelStateWriter == null ? ChannelStateWriter.NO_OP : channelStateWriter,
// Unknown channels exist only in BATCH jobs, which have no channel

@davidradl davidradl Sep 15, 2026

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I was expecting a change to the docs from the PR title. Is there an external consideration that we could add to the docs around this? Or is this just for code hygene?

@1996fanrui 1996fanrui Sep 17, 2026

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Hey @davidradl , I received some code review offline, and it mentioned that needsRecovery is always false in UnknownInputChannel is a risk that potentially missing the recovery path.

After analysis, the Unknown channels exist only in BATCH jobs, so this risk does not actually apply.

I’m inclined to add some documentation comments here to clarify this, ensuring that AI or developers can correctly understand the situation quickly, and avoid confusion.

// state, so this channel is never in recovery.
false);
return channel;
}
Expand All @@ -210,6 +212,8 @@ public LocalInputChannel toLocalInputChannel(ResultPartitionID resultPartitionID
metrics.getNumBuffersInLocalCounter(),
channelStateWriter == null ? ChannelStateWriter.NO_OP : channelStateWriter,
networkBuffersPerChannel,
// Unknown channels exist only in BATCH jobs, which have no channel
// state, so this channel is never in recovery.
false);
}

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