private static String getDefaultPrefix() {
    StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
    // 0: getStackTrace()
    // 1: getDefaultPrefix()
    // 2: newLock()
    // 3: caller of newLock()
    return stackTrace.length > 3
      ? stackTrace[3].getFileName() + ":" + stackTrace[3].getLineNumber()
      : "";
  }
If lock profiling is enabled, append summary statistics about lock usage to <code>sb</code>
@param sb the buffer to append the statistics to
ambari-server/src/main/java/org/apache/ambari/server/logging/LockFactory.java