Hazelcast log4j 配置产生“java.lang.NoClassDefFoundError: org/apache/log4j/Logger”错误

Question

I am trying to setup Hazelcast log4j logging on Windows using the latest version.

I added the config:

  <properties>
        <property name="hazelcast.logging.type">log4j</property>
  </properties>

I run the following command from the hazelcast bin folder:

java -jar ..\lib\hazelcast-3.12.2.jar com.hazelcast.core.server.StartServer

This produces the following error:

 Dec 20, 2019 8:44:56 AM com.hazelcast.config.AbstractConfigLocator
    INFO: Loading 'hazelcast.xml' from the working directory.
    Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Logger
            at com.hazelcast.logging.Log4jFactory.createLogger(Log4jFactory.java:29)
            at com.hazelcast.logging.LoggerFactorySupport$1.createNew(LoggerFactorySupport.java:32)
                ...
    Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger
            at java.net.URLClassLoader.findClass(Unknown Source)
                ...

I see that Hazelcast needs log4j version 1.2.17 so i downloaded that from maven and put it in a folder. I then ran the following:

 java -cp ..\..\log4j\log4j-1.2.17.jar -jar ..\lib\hazelcast-3.12.2.jar com.hazelcast.core.server.StartServer

However, I have read that you can't specify the classpath and the jar in the same statement. The hazelcast jars do not contain the log4j jar file. It seems that they should when packaged.

Can anyone help with this please.

Answer 1

In order to tell log4j how to get the config file, you must add the following line in the config file:

    <property name="log4j2.configuration">/path/to/properties/log4j2.properties</property>

so it looks like this:

  <properties>
        <property name="hazelcast.logging.type">log4j</property>
        <property name="log4j2.configuration">/path/to/properties/log4j2.properties</property>
  </properties>

Then you have to edit the log4j2.properties file, as stated in the documentation: https://docs.hazelcast.org/docs/latest/manual/html-single/index.html#logging-configuration