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https://issues.apache.org/jira/browse/HDFS-5381?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Colin Patrick McCabe updated HDFS-5381:
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Description: {{ExtendedBlock#hashCode}} contains both a block pool ID and a
block ID. The {{equals}} function checks both. However, {{hashCode}} only
uses block ID. Since HDFS-4645, block IDs are now allocated sequentially.
This means that there will be a lot of hash collisions when federation is in
use. We should use both block ID and block pool ID in {{hashCode}} to prevent
this. (was: {{ExtendedBlock#hashCode}} contains both a block pool ID and a
block ID. The {{equals}} function checks both. However, {{hashCode}} only
uses block ID. Since HDFS-4645, block pool IDs are now allocated sequentially.
This means that there will be a lot of hash collisions when federation is in
use. We should use both block ID and block pool ID in {{hashCode}} to prevent
this.)
> ExtendedBlock#hashCode should use both blockId and block pool ID
> ----------------------------------------------------------------
>
> Key: HDFS-5381
> URL: https://issues.apache.org/jira/browse/HDFS-5381
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode, namenode
> Affects Versions: 2.3.0
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Priority: Minor
>
> {{ExtendedBlock#hashCode}} contains both a block pool ID and a block ID. The
> {{equals}} function checks both. However, {{hashCode}} only uses block ID.
> Since HDFS-4645, block IDs are now allocated sequentially. This means that
> there will be a lot of hash collisions when federation is in use. We should
> use both block ID and block pool ID in {{hashCode}} to prevent this.
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