[
https://issues.apache.org/jira/browse/HDFS-13923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17479866#comment-17479866
]
tomscut commented on HDFS-13923:
--------------------------------
Based on what we have discussed above, I think the TODO comment can be removed.
What do you think? [~weichiu] [~xkrogen] [~csun]
{code:java}
// TODO : make this configurable or remove this variable
if (wrappedProxy instanceof ClientProtocol) {
this.observerReadEnabled = true;
} else {
LOG.info("Disabling observer reads for {} because the requested proxy "
+ "class does not implement {}", uri, ClientProtocol.class.getName());
this.observerReadEnabled = false;
} {code}
> Add a configuration to turn on/off observer reads
> -------------------------------------------------
>
> Key: HDFS-13923
> URL: https://issues.apache.org/jira/browse/HDFS-13923
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Chao Sun
> Assignee: Shweta
> Priority: Major
>
> In some situations having a config to turn on/off observer reads dynamically
> may be useful. For instance, some applications may be sensitive for data
> freshness and want to always reach directly to active NN. In a more complex
> scenario, services such as Presto may want to apply observer reads for
> different types of queries. In this case, simply change
> {{dfs.client.failover.proxy.provider.<nameservice>}} may not be enough, since
> with FileSystem cache (which is usually turned on) will ignore the change and
> still use the same FileSystem object.
> Here I'm proposing to add a flag in {{HdfsClientConfigKeys}}, such as
> {{dfs.client.observer.reads.enabled}}, that can be used to dynamically turn
> on/off observer reads. The FileSystem cache key should also take account of
> this flag in its {{hashCode}} and {{equals}} impl, so that different
> FileSystem objects will be used depending on the flag.
>
> cc [~shv], [~xkrogen], [~vagarychen], [~zero45] for discussion.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
