Crashes of RealVectorObservable on mpi reduce

reduce_test02.cpp

#include <alps/mc/mcbase.hpp>
#include <alps/mc/mcmpiadapter.hpp>
#include <alps/mc/api.hpp>
#include <alps/accumulator.hpp>
#include <alps/params.hpp>
#include <alps/utility/stop_callback.hpp>

class sim1 : public alps::mcbase {
    public:
        
        sim1(parameters_type const & p, std::size_t seed_offset = 0):
            alps::mcbase(p, seed_offset),
            nsweeps(p["nsweeps"]), 
            count(0) 
        {
            measurements << alps::accumulator::RealVectorObservable("e1");
            //measurements << alps::accumulator::RealVectorObservable("e2"); // doesn't play a role
        }

        void update() { count++; }
        void measure() { 
            measurements["e1"] << std::vector<double>(5, 1.0); 
            //measurements["e2"] << std::valarray<double>(4, 1.0); 
            //measurements["e2"] << std::vector<double>(5, 1.0);  // doesn't play a role
            }
        double fraction_completed() const { return double (count/nsweeps); }

    private:
        int nsweeps;
        int count;
};


int main(int argc, char* argv[])
{
    boost::mpi::environment env(argc, argv);
    boost::mpi::communicator comm;
    alps::params p; 
    p["nsweeps"] = 10000;
    alps::mcmpiadapter<sim1> sim (p,comm, alps::check_schedule(0.001, 60));
    sim.run(alps::stop_callback(1));
    alps::results_type<sim1>::type res = alps::collect_results(sim);
    std::cout << res << std::endl;
}