Tracing IBM MQ classes for Java applications

The trace facility in IBM® MQ classes for Java is provided to help IBM Support to diagnose customer issues. Various properties control the behavior of this facility.

About this task

If you are asked to provide trace output to investigate an issue, use one of the options mentioned below:

If you are unsure which option to use, contact your IBM Support representative and they will be able to advise you on the best way to collect trace for the issue you are seeing.

If a severe or unrecoverable error occurs, First Failure Support Technology (FFST) information is recorded in a file with a name of the format JAVACC xxxx.FDC where xxxx is a four-digit number. It is incremented to differentiate .FDC files.

.FDC files are always written to a subdirectory called FFDC. The subdirectory is in one of two locations, depending on whether trace is active:
Trace is active, and traceOutputName is set
The FFDC directory is created as a subdirectory of the directory to which the trace file is being written.
Trace is not active or traceOutputName is not set
The FFDC directory is created as a subdirectory of the current working directory.
The JSE common services uses java.util.logging as its trace and logging infrastructure. The root object of this infrastructure is the LogManager. The log manager has a reset method, which closes all handlers and sets the log level to null, which in effect turns off all the trace. If your application or application server calls java.util.logging.LogManager.getLogManager().reset(), it closes all trace, which might prevent you from diagnosing any problems. To avoid closing all trace, create a LogManager class with an overridden reset() method that does nothing, as in the following example. 

package com.ibm.javaut.tests;
import java.util.logging.LogManager;
public class JmsLogManager extends LogManager {
        // final shutdown hook to ensure that the trace is finally shutdown
        // and that the lock file is cleaned-up
        public class ShutdownHook extends Thread{
                public void run(){
                        doReset();
                }
        }
                public JmsLogManager(){
                // add shutdown hook to ensure final cleanup
                Runtime.getRuntime().addShutdownHook(new ShutdownHook());
        }
                public void reset() throws SecurityException {
                // does nothing
        }
        public void doReset(){
                super.reset();
        }
        }
The shutdown hook is necessary to ensure that trace is properly shutdown when the JVM finishes. To use the modified log manager instead of the default one, add a system property to the JVM startup: 

java -Djava.util.logging.manager=com. mycompany.logging.LogManager ...