message: Update hadoop_file_system.cc
  Add comment for  bug fix of hdfs max read length
diff: @@ -209,6 +209,8 @@ class HDFSRandomAccessFile : public RandomAccessFile {
  // We lock inside the loop rather than outside so we don't block other
  // concurrent readers.
  mutex_lock lock(mu_);
  + //Max read length is INT_MAX-2, for hdfsPread function take a parameter of int32.
  + //-2 offset can avoid JVM OutOfMemoryError.
  size_t read_n = std::min(n,static_cast<size_t>(std::numeric_limits<int>::max()-2));
  tSize r = hdfs_->hdfsPread(fs_, file_, static_cast<tOffset>(offset), dst,
  static_cast<tSize>(read_n));
  