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https://issues.apache.org/jira/browse/HDFS-16127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17379964#comment-17379964
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Kihwal Lee commented on HDFS-16127:
-----------------------------------
The proposed solution is to check the size of {{ackQueue}} when
{{waitForAllAcks()}} for the final packet throws an {{IOException}}. If the
queue is empty we can assume the last ack was received and the final packet for
the block was removed from the queue, meaning no recovery is needed.
> Improper pipeline close recovery causes a permanent write failure or data
> loss.
> -------------------------------------------------------------------------------
>
> Key: HDFS-16127
> URL: https://issues.apache.org/jira/browse/HDFS-16127
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Kihwal Lee
> Priority: Major
>
> When a block is being closed, the data streamer in the client waits for the
> final ACK to be delivered. If an exception is received during this wait, the
> close is retried. This assumption has become invalid by HDFS-15813, resulting
> in permanent write failures in some close error cases involving slow nodes.
> There are also less frequent cases of data loss.
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