cout defect

[Finomnis]

I have the problem that cout outputs get delayed for some reason.

I managed to break the problem down to a minimal example:

// Copyright (c)       2014 Martin Stumpf
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <hpx/hpx.hpp>
#include <hpx/hpx_init.hpp>
#include <hpx/include/iostreams.hpp>

void print_stuff()
{
    hpx::this_thread::sleep_for(boost::posix_time::milliseconds(1000));
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::this_thread::sleep_for(boost::posix_time::milliseconds(1000));
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
}

int hpx_main(boost::program_options::variables_map & vm)
{

    // The main scope
    {
            print_stuff();
            hpx::this_thread::sleep_for(boost::posix_time::milliseconds(5000));
    }

    // End the program
    return hpx::finalize();
}



//////////////////////////////////////////////////////////////////////////////
int main(int argc, char* argv[])
{
    // Configure application-specific options
    boost::program_options::options_description cmdline(
                                "Usage: " HPX_APPLICATION_STRING " [options]");

    return hpx::init(cmdline, argc, argv);
}

which produces the following output:

Adding workloads to queue ...
        Adding workload 10:10 ...
Adding workloads to queue ...
        Adding workload 10:10 ...
Adding workloads to queue ...
        Adding workload 10:10 ...
Adding workloads to queue ...
  <waits for 6 seconds>
        Adding workload 10:10 ...
        Adding workload 10:10 ...

The 6 seconds delay should be 1 second delay, followed by 5 seconds after printing the last two lines.

If tried changing the output text to different things, but as soon as I change it, it works.
Any ideas?

[Finomnis]

I ran it with both -t16 and -t1, the result is the same.

[Finomnis]

I changed the print function to that:

void print_stuff()
{

    hpx::this_thread::sleep_for(boost::posix_time::milliseconds(1000));
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 20 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 30 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 40 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 50 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 60 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 70 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 80 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 90 << ":" << 10 << " ..." << hpx::endl;
    hpx::this_thread::sleep_for(boost::posix_time::milliseconds(1000));
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;
    hpx::cout << "Adding workloads to queue ..." << hpx::endl;
    hpx::cout << "\tAdding workload " << 10 << ":" << 10 << " ..." << hpx::endl;

}

which produced this output:

Adding workloads to queue ...
        Adding workload 10:10 ...
Adding workloads to queue ...
        Adding workload 20:10 ...
Adding workloads to queue ...
        Adding workload 30:10 ...
Adding workloads to queue ...
        Adding workload 40:10 ...
Adding workloads to queue ...
        Adding workload 50:10 ...
Adding workloads to queue ...
        Adding workload 60:10 ...
Adding workloads to queue ...
        Adding workload 70:10 ...
Adding workloads to queue ...
        Adding workload 80:10 ...
Adding workloads to queue ...
<1 second delay>
        Adding workload 90:10 ...
Adding workloads to queue ...
        Adding workload 10:10 ...
Adding workloads to queue ...
        Adding workload 10:10 ...
Adding workloads to queue ...
<5 seconds delay>
        Adding workload 10:10 ...

Which doesn't make ANY sense to me.