modification to containerizer.cpp

if (!resources.mem().isSome()) {
    // No memory specified so probe OS or resort to DEFAULT_MEM.
    Bytes mem;
    Try<os::Memory> mem_ = os::memory();
    if (mem_.isError()) {
      LOG(WARNING) << "Failed to auto-detect the size of main memory: '"
                    << mem_.error()
                    << "' ; defaulting to DEFAULT_MEM";
      mem = DEFAULT_MEM;
    } else {
      mem = mem_.get().total;

      // Leave 1 GB free if we have more than 1 GB, otherwise, use all!
      // TODO(benh): Have better default scheme (e.g., % of mem not greater
      // than 1 GB?)
      if (mem > Gigabytes(1)) {
        mem = mem - Gigabytes(1);
      }
    }

    resources += Resources::parse(
        "mem",
        stringify(mem.megabytes()),
        flags.default_role).get();
  } else {
    // If memory specified
    Bytes mem ;
    // value of memory provided by user
    mem = resources.mem().get();
    Try<os::Memory> mem_ = os::memory();
    if (mem_.isError()) {
        //Error in main memory detection so using the default memory
    //check if the user specified memory is more than the Default memory
    if (mem > DEFAULT_MEM ) {
          LOG(WARNING) << "Failed to auto-detect the size of main memory: '"
                       << mem_.error()
                       << "' ; defaulting to DEFAULT_MEM"
               << "Resources specifies more than the default memory '"
                       << DEFAULT_MEM
                       << "' Defaulting to DEFAULT_MEM";
      mem = DEFAULT_MEM ;
        }

    } else {
        if (mem > mem_.get().total ) {
          LOG(WARNING) << "Resources specifies more than the main memory '"
                       << mem_.get().total.megabytes()
                       << "' Defaulting to main memory";
      mem = mem_.get().total ;
        }
    }
    //subtract the already parsed resources( memory ) and then
    resources -= Resources::parse(
        "mem",
        stringify(resources.mem().get().megabytes()),
        flags.default_role).get();

    //add the new value of resources
    resources += Resources::parse(
        "mem",
        stringify(mem.megabytes()),
        flags.default_role).get();

  }