From notifications-return-651-archive-asf-public=cust-asf.ponee.io@zookeeper.apache.org Fri Jul 5 16:42:50 2019 Return-Path: X-Original-To: archive-asf-public@cust-asf.ponee.io Delivered-To: archive-asf-public@cust-asf.ponee.io Received: from mail.apache.org (hermes.apache.org [207.244.88.153]) by mx-eu-01.ponee.io (Postfix) with SMTP id 1824B18057A for ; Fri, 5 Jul 2019 18:42:49 +0200 (CEST) Received: (qmail 97427 invoked by uid 500); 5 Jul 2019 16:42:49 -0000 Mailing-List: contact notifications-help@zookeeper.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: dev@zookeeper.apache.org Delivered-To: mailing list notifications@zookeeper.apache.org Received: (qmail 97418 invoked by uid 99); 5 Jul 2019 16:42:49 -0000 Received: from ec2-52-202-80-70.compute-1.amazonaws.com (HELO gitbox.apache.org) (52.202.80.70) by apache.org (qpsmtpd/0.29) with ESMTP; Fri, 05 Jul 2019 16:42:49 +0000 From: GitBox To: notifications@zookeeper.apache.org Subject: [GitHub] [zookeeper] jhuan31 commented on a change in pull request #986: ZOOKEEPER-3243: Add server-side request throttling Message-ID: <156234496424.3820.11947519371606759153.gitbox@gitbox.apache.org> Date: Fri, 05 Jul 2019 16:42:44 -0000 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit jhuan31 commented on a change in pull request #986: ZOOKEEPER-3243: Add server-side request throttling URL: https://github.com/apache/zookeeper/pull/986#discussion_r300745099 ########## File path: zookeeper-server/src/main/java/org/apache/zookeeper/server/RequestThrottler.java ########## @@ -0,0 +1,273 @@ +/** + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.zookeeper.server; + +import java.util.concurrent.LinkedBlockingQueue; + +import edu.umd.cs.findbugs.annotations.SuppressFBWarnings; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.zookeeper.common.Time; + +/** + * When enabled, the RequestThrottler limits the number of outstanding requests + * currently submitted to the request processor pipeline. The throttler augments + * the limit imposed by the globalOutstandingLimit that is enforced + * by the connection layer ({@link NIOServerCnxn}, {@link NettyServerCnxn}). + * + * The connection layer limit applies backpressure against the TCP connection by + * disabling selection on connections once the request limit is reached. However, + * the connection layer always allows a connection to send at least one request + * before disabling selection on that connection. Thus, in a scenario with 40000 + * client connections, the total number of requests inflight may be as high as + * 40000 even if the globalOustandingLimit was set lower. + * + * The RequestThrottler addresses this issue by adding additional queueing. When + * enabled, client connections no longer submit requests directly to the request + * processor pipeline but instead to the RequestThrottler. The RequestThrottler + * is then responsible for issuing requests to the request processors, and + * enforces a separate maxRequests limit. If the total number of + * outstanding requests is higher than maxRequests, the throttler + * will continually stall for stallTime milliseconds until + * underlimit. + * + * The RequestThrottler can also optionally drop stale requests rather than + * submit them to the processor pipeline. A stale request is a request sent + * by a connection that is already closed, and/or a request whose latency + * will end up being higher than its associated session timeout. The notion + * of staleness is configurable, @see Request for more details. + * + * To ensure ordering guarantees, if a request is ever dropped from a connection + * that connection is closed and flagged as invalid. All subsequent requests + * inflight from that connection are then dropped as well. + */ +public class RequestThrottler extends ZooKeeperCriticalThread { + private static final Logger LOG = LoggerFactory.getLogger(RequestThrottler.class); + + private final LinkedBlockingQueue submittedRequests = Review comment: :) ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: users@infra.apache.org With regards, Apache Git Services