Go to hazelcast.org/documentation

Logging Configuration

Hazelcast has a flexible logging configuration and does not depend on any logging framework except JDK logging. It has built-in adaptors for a number of logging frameworks and it also supports custom loggers by providing logging interfaces.

To use built-in adaptors, set the hazelcast.logging.type property to one of the predefined types below.

  • jdk: JDK logging (default)

  • log4j: Log4j

  • slf4j: Slf4j

  • none: disable logging

You can set hazelcast.logging.type through declarative configuration, programmatic configuration, or JVM system property.

image NOTE: If you choose to use log4j or slf4j, you should include the proper dependencies in the classpath.

Declarative Configuration

<hazelcast xsi:schemaLocation="http://www.hazelcast.com/schema/config
    http://www.hazelcast.com/schema/config/hazelcast-config-3.0.xsd"
    xmlns="http://www.hazelcast.com/schema/config"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

  ....

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

Programmatic Configuration

Config config = new Config() ;
config.setProperty( "hazelcast.logging.type", "log4j" );

System Property

-    Using JVM parameter: `java -Dhazelcast.logging.type=slf4j`
-    Using System class: `System.setProperty( "hazelcast.logging.type", "none" );`

If the provided logging mechanisms are not satisfactory, you can implement your own using the custom logging feature. To use it, implement the com.hazelcast.logging.LoggerFactory and com.hazelcast.logging.ILogger interfaces and set the system property hazelcast.logging.class as your custom LoggerFactory class name.

-Dhazelcast.logging.class=foo.bar.MyLoggingFactory

You can also listen to logging events generated by Hazelcast runtime by registering LogListeners to LoggingService.

LogListener listener = new LogListener() {
  public void log( LogEvent logEvent ) {
    // do something
  }
}
HazelcastInstance instance = Hazelcast.newHazelcastInstance();
LoggingService loggingService = instance.getLoggingService();
loggingService.addLogListener( Level.INFO, listener );

Through the LoggingService, you can get the currently used ILogger implementation and log your own messages too.

image NOTE: If you are not using command line for configuring logging, you should be careful about Hazelcast classes. They may be defaulted to jdk logging before newly configured logging is read. When logging mechanism is selected, it will not change.