You are viewing a plain text version of this content. The canonical link for it is here.
Posted to hdfs-dev@hadoop.apache.org by "Wei-Chiu Chuang (JIRA)" <ji...@apache.org> on 2019/02/15 01:31:00 UTC
[jira] [Created] (HDFS-14283) DFSInputStream to prefer cached
replica
Wei-Chiu Chuang created HDFS-14283:
--------------------------------------
Summary: DFSInputStream to prefer cached replica
Key: HDFS-14283
URL: https://issues.apache.org/jira/browse/HDFS-14283
Project: Hadoop HDFS
Issue Type: Improvement
Affects Versions: 2.6.0
Environment: HDFS Caching
Reporter: Wei-Chiu Chuang
HDFS Caching offers performance benefits. However, currently NameNode does not treat cached replica with higher priority, so HDFS caching is only useful when cache replication = 3, that is to say, all replicas are cached in memory, so that a client doesn't randomly pick an uncached replica.
HDFS-6846 proposed to let NameNode give higher priority to cached replica. Changing a logic in NameNode is always tricky so that didn't get much traction. Here I propose a different approach: let client (DFSInputStream) prefer cached replica.
A {{LocatedBlock}} object already contains cached replica location so a client has the needed information. I think we can change {{DFSInputStream#getBestNodeDNAddrPair()}} for this purpose.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: hdfs-dev-unsubscribe@hadoop.apache.org
For additional commands, e-mail: hdfs-dev-help@hadoop.apache.org