code: protected int getDepth() {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "getDepth");
  
      int depth;
  
      synchronized (barrier) {
         depth = queue.size();
      }
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "getDepth", depth);
      return depth;
    }
docs: Return the depth of the queue