[ https://issues.apache.org/jira/browse/ZOOKEEPER-4296?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Enrico Olivelli reassigned ZOOKEEPER-4296: ------------------------------------------ Assignee: Enrico Olivelli > NullPointerException when ClientCnxnSocketNetty is closed without being opened > ------------------------------------------------------------------------------ > > Key: ZOOKEEPER-4296 > URL: https://issues.apache.org/jira/browse/ZOOKEEPER-4296 > Project: ZooKeeper > Issue Type: Bug > Affects Versions: 3.5.9, 3.5.3, 3.6.3, 3.6.2 > Reporter: Colvin Cowie > Assignee: Enrico Olivelli > Priority: Minor > Labels: pull-request-available > Time Spent: 1.5h > Remaining Estimate: 0h > > I believe this bug was originally reported as ZOOKEEPER-2966 but that was > closed as not reproducible in February 2019. I left a comment with these > details on that issue in December. I can create a PR with a fix at some point > this week. > > In ZooKeeper 3.6.2, in the context of the SolrJ client, we hit the NPE > reported on ZOOKEEPER-2966 when a DNS error causes an exception after the > SolrZkClient trys to connect to ZooKeeper, but then immediately calls close > on the {{ClientCnxn}} > [https://github.com/apache/solr/blob/releases/lucene-solr%2F8.7.0/solr/solrj/src/java/org/apache/solr/common/cloud/SolrZkClient.java#L158-L204]. > {noformat} > java.lang.NullPointerException: null > at > org.apache.zookeeper.ClientCnxnSocketNetty.onClosing(ClientCnxnSocketNetty.java:247) > ~[zookeeper-3.6.2.jar:3.6.2] > at > org.apache.zookeeper.ClientCnxn$SendThread.close(ClientCnxn.java:1445) > ~[zookeeper-3.6.2.jar:3.6.2] > at org.apache.zookeeper.ClientCnxn.disconnect(ClientCnxn.java:1488) > ~[zookeeper-3.6.2.jar:3.6.2] > at org.apache.zookeeper.ClientCnxn.close(ClientCnxn.java:1517) > ~[zookeeper-3.6.2.jar:3.6.2] > at org.apache.zookeeper.ZooKeeper.close(ZooKeeper.java:1614) > ~[zookeeper-3.6.2.jar:3.6.2] > at > org.apache.solr.common.cloud.SolrZooKeeper.close(SolrZooKeeper.java:97) > ~[solr-solrj-8.7.0.jar:8.7.0 2dc63e901c60cda27ef3b744bc554f1481b3b067 - > atrisharma - 2020-10-29 19:39:18] > at > org.apache.solr.common.cloud.SolrZkClient.<init>(SolrZkClient.java:198) > ~[solr-solrj-8.7.0.jar:8.7.0 2dc63e901c60cda27ef3b744bc554f1481b3b067 - > atrisharma - 2020-10-29 19:39:18] > at > org.apache.solr.common.cloud.SolrZkClient.<init>(SolrZkClient.java:127) > ~[solr-solrj-8.7.0.jar:8.7.0 2dc63e901c60cda27ef3b744bc554f1481b3b067 - > atrisharma - 2020-10-29 19:39:18] > at > org.apache.solr.common.cloud.SolrZkClient.<init>(SolrZkClient.java:122) > ~[solr-solrj-8.7.0.jar:8.7.0 2dc63e901c60cda27ef3b744bc554f1481b3b067 - > atrisharma - 2020-10-29 19:39:18] > at > org.apache.solr.common.cloud.SolrZkClient.<init>(SolrZkClient.java:109) > ~[solr-solrj-8.7.0.jar:8.7.0 2dc63e901c60cda27ef3b744bc554f1481b3b067 - > atrisharma - 2020-10-29 19:39:18] > {noformat} > This happens if the {{ClientCnxnSocketNetty}}'s {{onClosing()}} is called > before {{connect(...)}} (or if connect isn't called at all) because the > {{firstConnect}} {{CountDownLatch}} is only initialized in {{connect(...)}}. > > [https://github.com/apache/zookeeper/blob/master/zookeeper-server/src/main/java/org/apache/zookeeper/ClientCnxnSocketNetty.java#L129] > > [https://github.com/apache/zookeeper/blob/master/zookeeper-server/src/main/java/org/apache/zookeeper/ClientCnxnSocketNetty.java#L247] > A null check in {{onClosing()}} will fix it, but I don't know if there's any > greater change required, e.g. some synchronization around connect and > onClosing. > The code in > [3.5.3|https://github.com/apache/zookeeper/blame/1507f67a06175155003722297daeb60bc912af1d/zookeeper-server/src/main/java/org/apache/zookeeper/ClientCnxnSocketNetty.java#L206] > looks very similar, it looks like it's been present since the initial commit > of {{ClientCnxnSocketNetty}}. -- This message was sent by Atlassian Jira (v8.20.10#820010)