From dev-return-67563-archive-asf-public=cust-asf.ponee.io@zookeeper.apache.org Thu Feb 15 20:14:20 2018 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 [140.211.11.3]) by mx-eu-01.ponee.io (Postfix) with SMTP id E72E218064A for ; Thu, 15 Feb 2018 20:14:19 +0100 (CET) Received: (qmail 53506 invoked by uid 500); 15 Feb 2018 19:14:18 -0000 Mailing-List: contact dev-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 dev@zookeeper.apache.org Received: (qmail 53495 invoked by uid 99); 15 Feb 2018 19:14:18 -0000 Received: from pnap-us-west-generic-nat.apache.org (HELO spamd3-us-west.apache.org) (209.188.14.142) by apache.org (qpsmtpd/0.29) with ESMTP; Thu, 15 Feb 2018 19:14:18 +0000 Received: from localhost (localhost [127.0.0.1]) by spamd3-us-west.apache.org (ASF Mail Server at spamd3-us-west.apache.org) with ESMTP id 46FF4180146 for ; Thu, 15 Feb 2018 19:14:18 +0000 (UTC) X-Virus-Scanned: Debian amavisd-new at spamd3-us-west.apache.org X-Spam-Flag: NO X-Spam-Score: -109.511 X-Spam-Level: X-Spam-Status: No, score=-109.511 tagged_above=-999 required=6.31 tests=[ENV_AND_HDR_SPF_MATCH=-0.5, KAM_ASCII_DIVIDERS=0.8, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001, T_RP_MATCHES_RCVD=-0.01, USER_IN_DEF_SPF_WL=-7.5, USER_IN_WHITELIST=-100] autolearn=disabled Received: from mx1-lw-us.apache.org ([10.40.0.8]) by localhost (spamd3-us-west.apache.org [10.40.0.10]) (amavisd-new, port 10024) with ESMTP id Y2x9-Q1sBTUa for ; Thu, 15 Feb 2018 19:14:16 +0000 (UTC) Received: from mailrelay1-us-west.apache.org (mailrelay1-us-west.apache.org [209.188.14.139]) by mx1-lw-us.apache.org (ASF Mail Server at mx1-lw-us.apache.org) with ESMTP id 3D3875FDCD for ; Thu, 15 Feb 2018 19:14:11 +0000 (UTC) Received: from jira-lw-us.apache.org (unknown [207.244.88.139]) by mailrelay1-us-west.apache.org (ASF Mail Server at mailrelay1-us-west.apache.org) with ESMTP id F0272E0428 for ; Thu, 15 Feb 2018 19:14:08 +0000 (UTC) Received: from jira-lw-us.apache.org (localhost [127.0.0.1]) by jira-lw-us.apache.org (ASF Mail Server at jira-lw-us.apache.org) with ESMTP id CB5BA24231 for ; Thu, 15 Feb 2018 19:14:05 +0000 (UTC) Date: Thu, 15 Feb 2018 19:14:05 +0000 (UTC) From: "ASF GitHub Bot (JIRA)" To: dev@zookeeper.apache.org Message-ID: In-Reply-To: References: Subject: [jira] [Commented] (ZOOKEEPER-2184) Zookeeper Client should re-resolve hosts when connection attempts fail MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-JIRA-FingerPrint: 30527f35849b9dde25b450d4833f0394 [ https://issues.apache.org/jira/browse/ZOOKEEPER-2184?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16366137#comment-16366137 ] ASF GitHub Bot commented on ZOOKEEPER-2184: ------------------------------------------- Github user afine commented on a diff in the pull request: https://github.com/apache/zookeeper/pull/451#discussion_r168576090 --- Diff: src/java/main/org/apache/zookeeper/client/StaticHostProvider.java --- @@ -47,59 +51,169 @@ private int currentIndex = -1; + // Don't re-resolve on first next() call + private boolean connectedSinceNext = true; + + private Resolver resolver; + /** * Constructs a SimpleHostSet. - * + * * @param serverAddresses * possibly unresolved ZooKeeper server addresses * @throws IllegalArgumentException * if serverAddresses is empty or resolves to an empty list */ public StaticHostProvider(Collection serverAddresses) { + this.resolver = new Resolver() { + @Override + public InetAddress[] getAllByName(String name) throws UnknownHostException { + return InetAddress.getAllByName(name); + } + }; + init(serverAddresses); + } + + /** + * Introduced for testing purposes. getAllByName() is a static method of InetAddress, therefore cannot be easily mocked. + * By abstraction of Resolver interface we can easily inject a mocked implementation in tests. + * + * @param serverAddresses + * possibly unresolved ZooKeeper server addresses + * @param resolver + * custom resolver implementation + * @throws IllegalArgumentException + * if serverAddresses is empty or resolves to an empty list + */ + public StaticHostProvider(Collection serverAddresses, Resolver resolver) { + this.resolver = resolver; + init(serverAddresses); + } + + /** + * Common init method for all constructors. + * Resolve all unresolved server addresses, put them in a list and shuffle. + */ + private void init(Collection serverAddresses) { for (InetSocketAddress address : serverAddresses) { try { - InetAddress ia = address.getAddress(); - InetAddress resolvedAddresses[] = InetAddress.getAllByName((ia != null) ? ia.getHostAddress() : - address.getHostName()); + InetAddress resolvedAddresses[] = this.resolver.getAllByName(getHostString(address)); for (InetAddress resolvedAddress : resolvedAddresses) { - // If hostName is null but the address is not, we can tell that - // the hostName is an literal IP address. Then we can set the host string as the hostname - // safely to avoid reverse DNS lookup. - // As far as i know, the only way to check if the hostName is null is use toString(). - // Both the two implementations of InetAddress are final class, so we can trust the return value of - // the toString() method. - if (resolvedAddress.toString().startsWith("/") - && resolvedAddress.getAddress() != null) { - this.serverAddresses.add( - new InetSocketAddress(InetAddress.getByAddress( - address.getHostName(), - resolvedAddress.getAddress()), - address.getPort())); - } else { - this.serverAddresses.add(new InetSocketAddress(resolvedAddress.getHostAddress(), address.getPort())); - } + this.serverAddresses.add(new InetSocketAddress(resolvedAddress, address.getPort())); } } catch (UnknownHostException e) { LOG.error("Unable to connect to server: {}", address, e); } } - + if (this.serverAddresses.isEmpty()) { throw new IllegalArgumentException( "A HostProvider may not be empty!"); } + Collections.shuffle(this.serverAddresses); } + /** + * Evaluate to a hostname if one is available and otherwise it returns the + * string representation of the IP address. + * + * In Java 7, we have a method getHostString, but earlier versions do not support it. + * This method is to provide a replacement for InetSocketAddress.getHostString(). + * + * @param addr + * @return Hostname string of address parameter + */ + private String getHostString(InetSocketAddress addr) { + String hostString = ""; + + if (addr == null) { + return hostString; + } + if (!addr.isUnresolved()) { + InetAddress ia = addr.getAddress(); + + // If the string starts with '/', then it has no hostname + // and we want to avoid the reverse lookup, so we return + // the string representation of the address. + if (ia.toString().startsWith("/")) { + hostString = ia.getHostAddress(); + } else { + hostString = addr.getHostName(); + } + } else { + // According to the Java 6 documentation, if the hostname is + // unresolved, then the string before the colon is the hostname. + String addrString = addr.toString(); + hostString = addrString.substring(0, addrString.lastIndexOf(':')); + } + + return hostString; + } + public int size() { return serverAddresses.size(); } + // Counts the number of addresses added and removed during + // the last call to next. Used mainly for test purposes. + // See StasticHostProviderTest. + private int nextAdded = 0; --- End diff -- instead of exposing all these metrics, which involve making changes to application logic. Why don't we just expose the `serverAddresses` to the test? > Zookeeper Client should re-resolve hosts when connection attempts fail > ---------------------------------------------------------------------- > > Key: ZOOKEEPER-2184 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2184 > Project: ZooKeeper > Issue Type: Bug > Components: java client > Affects Versions: 3.4.6, 3.4.7, 3.4.8, 3.4.9, 3.4.10, 3.5.0, 3.5.1, 3.5.2, 3.5.3, 3.4.11 > Environment: Ubuntu 14.04 host, Docker containers for Zookeeper & Kafka > Reporter: Robert P. Thille > Assignee: Flavio Junqueira > Priority: Blocker > Labels: easyfix, patch > Fix For: 3.5.4, 3.4.12 > > Attachments: ZOOKEEPER-2184.patch > > > Testing in a Docker environment with a single Kafka instance using a single Zookeeper instance. Restarting the Zookeeper container will cause it to receive a new IP address. Kafka will never be able to reconnect to Zookeeper and will hang indefinitely. Updating DNS or /etc/hosts with the new IP address will not help the client to reconnect as the zookeeper/client/StaticHostProvider resolves the connection string hosts at creation time and never re-resolves. > A solution would be for the client to notice that connection attempts fail and attempt to re-resolve the hostnames in the connectString. -- This message was sent by Atlassian JIRA (v7.6.3#76005)