[FLINK-20404] ZooKeeper quorum fails to start due to missing log4j library

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: 1.11.2
• Fix Version/s: 1.11.3, 1.12.1, 1.13.0
• Component/s: Build System
• Labels: pull-request-available

Release Note

The Zookeeper scripts in the Flink distribution have been modified to disable the Log4j JMX integration due to an incompatibility between Zookeeper 3.4 and Log4j 2.
To re-enable this feature, remove the line in the "zookeeper.sh" file that sets "zookeeper.jmx.log4j.disable".

• Assignee: Chesnay Schepler
• Reporter: Pedro Miguel Rainho Chaves
• Created: 27/Nov/20 15:14
• Updated: 07/Dec/20 20:15
• Resolved: 07/Dec/20 20:15

Description

Upon starting a zookeeper quorum using flink's bootstrapped zookeeper, it throws the following exception.

 

2020-11-27 13:13:38,371 ERROR org.apache.flink.runtime.zookeeper.FlinkZooKeeperQuorumPeer  [] - Error running ZooKeeper quorum peer: org/apache/log4j/jmx/HierarchyDynamicMBean
java.lang.NoClassDefFoundError: org/apache/log4j/jmx/HierarchyDynamicMBean
        at org.apache.flink.shaded.zookeeper3.org.apache.zookeeper.jmx.ManagedUtil.registerLog4jMBeans(ManagedUtil.java:51) ~[flink-shaded-zookeeper-3.4.14.jar:3.4.14-11.0]
        at org.apache.flink.shaded.zookeeper3.org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:125) ~[flink-shaded-zookeeper-3.4.14.jar:3.4.14-11.0]
        at org.apache.flink.runtime.zookeeper.FlinkZooKeeperQuorumPeer.runFlinkZkQuorumPeer(FlinkZooKeeperQuorumPeer.java:123) ~[flink-dist_2.11-1.11.2.jar:1.11.2]
        at org.apache.flink.runtime.zookeeper.FlinkZooKeeperQuorumPeer.main(FlinkZooKeeperQuorumPeer.java:79) [flink-dist_2.11-1.11.2.jar:1.11.2]
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.jmx.HierarchyDynamicMBean
        at java.net.URLClassLoader.findClass(URLClassLoader.java:382) ~[?:1.8.0_262]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:418) ~[?:1.8.0_262]
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:352) ~[?:1.8.0_262]
        at java.lang.ClassLoader.loadClass(ClassLoader.java:351) ~[?:1.8.0_262]
        ... 4 more

This happens because the new flink version is missing a log4j library. This can be solved by adding log4j-1.2.17.jar to the classpath, nonetheless the bootstrapped zookeepeer version should be compatible with the log4j2 libraries that come with flink's default installation.

 

Steps to reproduce:

1. Fresh install of flink version 1.11.2 
2. Change the zookeeper config to start as a quorum

   server.1=<hostname>:2888:3888
   server.2=<hostname>:2888:3888

1. Start zookeeper
2. <installation_path>/bin/zookeeper.sh start-foreground 1

Issue Links

• links to: GitHub Pull Request #14302