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Posted to hdfs-issues@hadoop.apache.org by "Yiqun Lin (Jira)" <ji...@apache.org> on 2020/11/06 06:59:00 UTC
[jira] [Comment Edited] (HDFS-14090) RBF: Improved isolation for
downstream name nodes. {Static}
[ https://issues.apache.org/jira/browse/HDFS-14090?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17227189#comment-17227189 ]
Yiqun Lin edited comment on HDFS-14090 at 11/6/20, 6:58 AM:
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Hi [~fengnanli], some minor comments from me:
1. I see here we introduce CONCURRENT_NS for concurrent call, why not acquire permit to corresponding ns instead of?
2. Current description of setting hdfs-rbf-default.xml can describe more. At least, we need to mention:
* The setting name for how to configure handler count for each ns, also include CONCURRENT_NS ns.
* The sum of dedicated handler count should be less than value of dfs.federation.router.handler.count
3. It would be better to add this improvement in HDFSRouterFederation.md.
Comment #2 and #3 can be addressed in a follow-up JIRA, :).
was (Author: linyiqun):
Hi [~fengnanli], some minor comments from me:
1. I see here we introduce CONCURRENT_NS for concurrent call, why not acquire permit to corresponding ns instead of?
2. Current description of setting hdfs-rbf-default.xml can describe more. At least, we need to mention:
* The setting name for how to configure handler count for each ns, also include CONCURRENT_NS ns.
* The sum of dedicated handler count should be less than value of dfs.federation.router.handler.count
3. It would be better to add this improvement in HDFSRouterFederation.md.
> RBF: Improved isolation for downstream name nodes. {Static}
> -----------------------------------------------------------
>
> Key: HDFS-14090
> URL: https://issues.apache.org/jira/browse/HDFS-14090
> Project: Hadoop HDFS
> Issue Type: New Feature
> Reporter: CR Hota
> Assignee: Fengnan Li
> Priority: Major
> Attachments: HDFS-14090-HDFS-13891.001.patch, HDFS-14090-HDFS-13891.002.patch, HDFS-14090-HDFS-13891.003.patch, HDFS-14090-HDFS-13891.004.patch, HDFS-14090-HDFS-13891.005.patch, HDFS-14090.006.patch, HDFS-14090.007.patch, HDFS-14090.008.patch, HDFS-14090.009.patch, HDFS-14090.010.patch, HDFS-14090.011.patch, HDFS-14090.012.patch, HDFS-14090.013.patch, HDFS-14090.014.patch, HDFS-14090.015.patch, HDFS-14090.016.patch, HDFS-14090.017.patch, HDFS-14090.018.patch, HDFS-14090.019.patch, HDFS-14090.020.patch, HDFS-14090.021.patch, HDFS-14090.022.patch, HDFS-14090.023.patch, RBF_ Isolation design.pdf
>
>
> Router is a gateway to underlying name nodes. Gateway architectures, should help minimize impact of clients connecting to healthy clusters vs unhealthy clusters.
> For example - If there are 2 name nodes downstream, and one of them is heavily loaded with calls spiking rpc queue times, due to back pressure the same with start reflecting on the router. As a result of this, clients connecting to healthy/faster name nodes will also slow down as same rpc queue is maintained for all calls at the router layer. Essentially the same IPC thread pool is used by router to connect to all name nodes.
> Currently router uses one single rpc queue for all calls. Lets discuss how we can change the architecture and add some throttling logic for unhealthy/slow/overloaded name nodes.
> One way could be to read from current call queue, immediately identify downstream name node and maintain a separate queue for each underlying name node. Another simpler way is to maintain some sort of rate limiter configured for each name node and let routers drop/reject/send error requests after certain threshold.
> This won’t be a simple change as router’s ‘Server’ layer would need redesign and implementation. Currently this layer is the same as name node.
> Opening this ticket to discuss, design and implement this feature.
>
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