Haohui Mai created HDFS-5891:
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Summary: webhdfs should not try connecting the DN during
redirection
Key: HDFS-5891
URL: https://issues.apache.org/jira/browse/HDFS-5891
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Haohui Mai
Assignee: Haohui Mai
When the webhdfs server in NN serves an {{OPEN}} request, the NN will
eventually redirect the request to a DN. The current implementation intends to
choose the active DNs. The code always connects to the DN in a deterministic
order to see whether it is active during redirection.
Although it reduces the chance of the client from connecting to a failed DN,
this is problematic because:
# It has no guarantees that the client can connect to that DN even if the NN
can connect to it.
# It requires an additional network round-trip for every {{OPEN}} / {{CREATE}}
request.
This jira proposes that the NN should choose the DN based on the information of
the data node manager.
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