Description
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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Attachments
Issue Links
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HDFS-14749 RBF: Isolation across multiple downstream hdfs clusters
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- Open
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- Resolved
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- Resolved
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HDFS-15863 RBF: Validation message to be corrected in FairnessPolicyController
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- Resolved
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