code: public String dumpStats() {
          int heapArenasLen = heapArenas == null ? 0 : heapArenas.length;
          StringBuilder buf = new StringBuilder(512)
                  .append(heapArenasLen)
                  .append(" heap arena(s):")
                  .append(StringUtil.NEWLINE);
          if (heapArenasLen > 0) {
              for (PoolArena<byte[]> a: heapArenas) {
                  buf.append(a);
              }
          }
  
          int directArenasLen = directArenas == null ? 0 : directArenas.length;
  
          buf.append(directArenasLen)
             .append(" direct arena(s):")
             .append(StringUtil.NEWLINE);
          if (directArenasLen > 0) {
              for (PoolArena<ByteBuffer> a: directArenas) {
                  buf.append(a);
              }
          }
  
          return buf.toString();
      }
docs: Returns the status of the allocator (which contains all metrics) as string. Be aware this may be expensive
  and so should not called too frequently.