Occasionally when you are troubleshooting an issue with a clustered deployment, you may find it helpful to use additional information from the Couchbase Java SDK logging. The SDK uses JDK logging and this can be configured by specifying a runtime define and adding some additional logging properties. There are two ways to set up Java SDK logging:

To provide logging via spymemcached:

System.setProperty("net.spy.log.LoggerImpl", "net.spy.memcached.compat.log.SunLogger");

or

System.setProperty("net.spy.log.LoggerImpl", "net.spy.memcached.compat.log.Log4JLogger");

The default logger simply logs everything to the standard error stream. To provide logging via the JDK, if you are running a command-line Java program, you can run the program with logging by setting a property:

-Djava.util.logging.config.file=logging.properties

The other alternative is create a logging.properties and add it to your in your classpath:

logging.properties
handlers = java.util.logging.ConsoleHandler
java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = java.util.logging.SimpleFormatter
com.couchbase.client.vbucket.level = FINEST
com.couchbase.client.vbucket.config.level = FINEST
com.couchbase.client.level = FINEST

The final option is to provide logging from your actual Java application. If you are writing your application in an IDE which manages command-line operations for you, it may be easier if you express logging in your application code. Here is an example:

// Tell things using spymemcached logging to use internal SunLogger API
        Properties systemProperties = System.getProperties();
        systemProperties.put("net.spy.log.LoggerImpl", "net.spy.memcached.compat.log.SunLogger");
        System.setProperties(systemProperties);

        Logger.getLogger("net.spy.memcached").setLevel(Level.FINEST);
        Logger.getLogger("com.couchbase.client").setLevel(Level.FINEST);
        Logger.getLogger("com.couchbase.client.vbucket").setLevel(Level.FINEST);

        //get the top Logger
        Logger topLogger = java.util.logging.Logger.getLogger("");

        // Handler for console (reuse it if it already exists)
        Handler consoleHandler = null;
        //see if there is already a console handler
        for (Handler handler : topLogger.getHandlers()) {
            if (handler instanceof ConsoleHandler) {
                //found the console handler
                consoleHandler = handler;
                break;
            }
        }

        if (consoleHandler == null) {
            //there was no console handler found, create a new one
            consoleHandler = new ConsoleHandler();
            topLogger.addHandler(consoleHandler);
        }

        //set the console handler to fine:
        consoleHandler.setLevel(java.util.logging.Level.FINEST);