Add vector to vector with maximum performance [duplicate]

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• C++ push_back vs Insert vs emplace 3 answers

I am creating a vector in different thread. After that I want to pass it to the method Data::insert() that saves this vector in another vector. What is the optimal way to do that?

template<typename DATA_TYPE>
class Data
{
public:
    Data();

    void insert(vector<DATA_TYPE>& d)
    {
        if (d.empty())
            throw range_error("Data::insert(): Vector is empty!");

        lock_guard<mutex> l(data_mutex_);
        // Add d to the vector data_
    }
private:
    vector<vector<DATA_TYPE>> data_;

    mutex data_mutex_;
};