+1 -Ayush
> On 14 Feb 2025, at 1:20 PM, Hui Fei <feihui.u...@gmail.com> wrote: > > Did some test work referring to the documentation. > > - Compiled source codes, built a local cluster and the async feature > worked fine. > - it is disabled by default > - can increase or decrease the thread number by changing the related > configurations > > +1 > > jian zhang <keeprom...@apache.org> 于2025年2月14日周五 15:21写道： > >> 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. >> --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-dev-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-dev-h...@hadoop.apache.org
