+1. Thanks to the developers for the great work. This is a great enhancement to the system.
Best regards, - Hualong Zhang ________________________________ From: slfan1989 <slfan1...@apache.org> Sent: Saturday, February 15, 2025 10:40 To: jian zhang <keeprom...@apache.org> Cc: Hdfs-dev <hdfs-dev@hadoop.apache.org>; <priv...@hadoop.apache.org> <priv...@hadoop.apache.org>; Xiaoqiao He <hexiaoq...@apache.org>; common-...@hadoop.apache.org <common-...@hadoop.apache.org>; Hui Fei <feihui.u...@gmail.com>; hfutzhan...@163.com <hfutzhan...@163.com> Subject: Re: [VOTE] Request to merge branch HDFS-17531 into trunk. +1 Best Regards, - Shilun Fan On Fri, Feb 14, 2025 at 3:22 PM jian zhang <keeprom...@apache.org> wrote: > Hi, all, the development of the asynchronous router functionality has been > completed. Thanks to all the contributors who participated in this feature. > The development branch is HDFS-17531, and it is ready to be merged into the > trunk branch. > > JIRA: HDFS-17531 https://issues.apache.org/jira/browse/HDFS-17531 > PR: https://github.com/apache/hadoop/pull/7308 > > DISCUSS: https://lists.apache.org/thread/02y3dtpfxt21bxjgmyl3kxnv4m1vwz44 > > Here is the functionality introduction of the asynchronous router for > everyone to review: > I. Overview > > The asynchronous router aims to address the performance bottleneck > issues of the synchronous router in high - concurrency and multi - > nameservices scenarios. By introducing an asynchronous processing > mechanism, it optimizes the request handling process, improves the system's > concurrency ability and resource utilization, and is particularly suitable > for the federated scenarios where multiple downstream services (NS) need to > be processed. > > II. Problems of the Synchronous Router > > - Performance Bottleneck: The performance of the synchronous router is > limited by the number of handler threads. Even if the connection thread can > still forward requests to the downstream namenode, the handler must wait > for each request to complete before processing the next one, resulting in > limited processing capacity. > - Thread Resource Waste: To improve performance, increasing the number > of handler threads will lead to more thread switches, which instead reduces > the system efficiency. At the same time, a large number of handler threads > are in a blocked state, wasting thread resources. > - Poor Isolation in Multi - ns: If the performance of a certain > nameservice in the downstream nameservice is poor, it will cause the > handler to wait for a long time, thus affecting the forwarding of requests > to other normal - performance ns, resulting in a decrease in the overall > performance of the downstream ns services perceived by the client. > - Ineffective Utilization of Federation Multi - ns Performance: In high > - concurrency scenarios, a large number of requests may be backlogged in > the router's request queue, while the queues of downstream services are not > fully utilized, leading to unreasonable resource allocation. > > III. Design and Improvements of the Asynchronous Router > > The asynchronous router solves the above problems by redesigning the > request handling process and introducing an asynchronous processing > mechanism. Its core improvements include: > > - Handler: Retrieves requests from the request queue for preliminary > processing. If there are exceptions in the request (such as the mount point > does not exist, etc.), it directly puts the response into the response > queue; otherwise, it sends the request to the asynchronous handler thread > pool. > - Async Handler: Puts the request into the call queue > (connection.calls) of the connection thread and returns immediately without > blocking and waiting. > - Async Responder: Is responsible for processing the responses received > by the connection thread. If the request needs to be re - initiated (such > as the downstream service returns a standby exception), it re - adds the > request to the asynchronous handler thread pool; otherwise, it puts the > response into the response queue. > - Responder: Retrieves the response from the response queue and returns > it to the client. > > IV. Advantages of the Asynchronous Router > > - High - Concurrency Performance: Through the asynchronous processing > mechanism, the asynchronous router can handle a large number of requests > simultaneously, significantly improving the system's concurrent processing > ability. > - High Resource Utilization: It avoids thread blocking and frequent > switching, reduces thread resource waste, and improves the overall > efficiency of the system. > - Isolation: Different ns are processed by different async handler > thread pools, achieving isolation of different downstream services. Even if > the performance of a certain service is poor, it will not affect the > processing ability of other services. > > V. Summary > > The asynchronous router solves the performance bottleneck problem of > the traditional synchronous router in high - concurrency scenarios by > introducing an asynchronous processing mechanism. It not only improves the > system's concurrency ability and resource utilization but also achieves > isolation of downstream services through the queue mechanism, enhancing the > system's stability and adaptability. In the federated scenarios where > multiple downstream services need to be processed, the asynchronous router > is a more efficient and reliable solution. > VI. Performance Testing > > > > https://docs.google.com/document/d/1meHOCvhm3XRHlIMwvKFidfUSjveTJrb8yAMasrM_HrY/edit?tab=t.0#heading=h.du0zlo2k5sb1 > > VII. JIRA & RPs > > For more information, please refer to JIRA: > JIRA: RBF: Asynchronous router RPC: > https://issues.apache.org/jira/browse/HDFS-17531 > PRs: > HDFS-17543. [ARR] AsyncUtil makes asynchronous code more concise and > easier. > HADOOP-19235. IPC client uses CompletableFuture to support asynchronous > operations. > HDFS-17544. [ARR] The router client rpc protocol PB supports > asynchrony. > HDFS-17545. [ARR] router async rpc client. > HDFS-17594. [ARR] RouterCacheAdmin supports asynchronous rpc. > HDFS-17597. [ARR] RouterSnapshot supports asynchronous rpc. > HDFS-17595. [ARR] ErasureCoding supports asynchronous rpc. > HDFS-17601. [ARR] RouterRpcServer supports asynchronous rpc. > HDFS-17596. [ARR] RouterStoragePolicy supports asynchronous rpc. > HDFS-17656. [ARR] RouterNamenodeProtocol and RouterUserProtocol > supports asynchronous rpc. > HDFS-17659. [ARR]Router Quota supports asynchronous rpc. > HDFS-17672. [ARR] Move asynchronous related classes to the async > package. > HADOOP-19361. RPC DeferredMetrics bugfix. > HDFS-17640.[ARR] RouterClientProtocol supports asynchronous rpc. > HDFS-17650. [ARR] The router server-side rpc protocol PB supports > asynchrony. > HDFS-17651.[ARR] Async handler executor isolation. > HDFS-17715. [ARR] Add documentation for asynchronous router. >
