Debug multithreading issues with logging: Formatter that prints thread ID and milliseconds

threadlogging.java

Logger.getLogger("").setLevel(Level.ALL);
final ConsoleHandler consoleHandler = new ConsoleHandler();
consoleHandler.setFormatter(
    new Formatter() {
      private final MessageFormat messageFormat =
          new MessageFormat("[{0,date,hh:mm:ss.SSS} {1} {2} {3}] {4}{5}\n", Locale.ROOT);

      @Override
      public String format(LogRecord record) {
        final String backtrace;
        if (record.getThrown() != null) {
          final StringWriter sw = new StringWriter();
          final PrintWriter pw = new PrintWriter(sw);
          record.getThrown().printStackTrace(pw);
          pw.flush();
          backtrace = sw.toString();
        } else {
          backtrace = null;
        }
        return messageFormat.format(
            new Object[] {
              new Date(record.getMillis()),
              record.getLoggerName(),
              record.getThreadID(),
              record.getLevel().getName(),
              new MessageFormat(record.getMessage(), Locale.ROOT)
                  .format(record.getParameters()),
              backtrace == null ? "" : "\n" + backtrace
            });
      }
    });
consoleHandler.setLevel(Level.ALL);
Logger.getLogger("").addHandler(consoleHandler);