code: public final MappedByteBuffer load() {
          checkMapped();
          if ((address == 0) || (capacity() == 0))
              return this;
          long offset = mappingOffset();
          long length = mappingLength(offset);
          load0(mappingAddress(offset), length);
  
          // Read a byte from each page to bring it into memory. A checksum
          // is computed as we go along to prevent the compiler from otherwise
          // considering the loop as dead code.
          Unsafe unsafe = Unsafe.getUnsafe();
          int ps = Bits.pageSize();
          int count = Bits.pageCount(length);
          long a = mappingAddress(offset);
          byte x = 0;
          for (int i = 0; i < count; i++) {
              x ^= unsafe.getByte(a);
              a += ps;
          }
          if (unused != 0)
              unused = x;
  
          return this;
      }
docs: Loads this buffer's content into physical memory.
  
  <p> This method makes a best effort to ensure that, when it returns,
  this buffer's content is resident in physical memory.  Invoking this
  method may cause some number of page faults and I/O operations to
  occur. </p>
  
  @return This buffer