HPX counters crashing the application

[xaguilar]

Using HPX counters in a std::thread makes the program crash.

I create an additional thread to sample some HPX counters with a certain frequency using:

sampler_thread = std::thread(&my_sampling_funct, this);

Then if I create/use a counter in my_sampling_funct, the program crashes.

• HPX Version: latest
• Platform (compiler, OS): gcc 7.2.0, CentOS 7.4.1708

[hkaiser]

Could you provide us with a small reproducing test case for this. The way you describe it does not allow for any diagnostics or even fixing. Thanks.

[RANJEET16520]

Could you give any kind of test case. I am not understand even where it will crash so don't know how to fix it. Thanks

[hkaiser]

@RANJEET16520 I didn't ask you to fix it. I asked you to give us some code that allows us to reproduce the problem you're seeing.

[xaguilar]

Hi all, I'm sorry that I wasn't clear enough when I opened the issue. Please find below a simplified example where this error occurs.

#include <hpx/hpx_init.hpp>
#include <hpx/include/performance_counters.hpp>
#include <iostream>
#include <thread>

#include <boost/format.hpp>

hpx::id_type idle_rate_counter_;

void my_sampling_funct(void)
{
    // Create one counter per locality
    static const char* idle_counter_name =
        "/threads{locality#%d/total}/idle-rate";

    const std::uint32_t prefix = hpx::get_locality_id();

    std::cerr << "Registering counter "
              << boost::str(boost::format(idle_counter_name) % prefix)
              << std::endl;
    idle_rate_counter_ = hpx::performance_counters::get_counter(
        boost::str(boost::format(idle_counter_name) % prefix));

    // Start the counter
    hpx::performance_counters::stubs::performance_counter::start(
        hpx::launch::sync, idle_rate_counter_);

    // Get the value
    hpx::performance_counters::counter_value idle_value =
        hpx::performance_counters::stubs::performance_counter::get_value(
            hpx::launch::sync, idle_rate_counter_);

    double idle_rate_ = idle_value.get_value<double>() * 0.01;

    std::cout << "Idle rate: " << idle_rate_ << std::endl;

    // Stop the counter
    hpx::performance_counters::stubs::performance_counter::stop(
        hpx::launch::sync, idle_rate_counter_);
}

int hpx_main(int argc, char** argv)
{
    // Create one additional OS-thread
    std::thread sampler_thread = std::thread(&my_sampling_funct);

    sampler_thread.join();

    hpx::finalize();

    //std::terminate();
    return 0;
}

int main(int argc, char** argv)
{
    return hpx::init();
}

Please don't hesitate to ask me again if you need further assistance. Thanks!

[RANJEET16520]

Thanks sir

[hkaiser]

@RANJEET16520 Thanks for the code snippet. I'm not sure why you decided to create a new (kernel-) thread for your test function. I would advise not to do that. You should create an HPX thread instead. Either simply switch std::thread for hpx::thread or use hpx::async to launch your function on a new HPX thread. I personally prefer the latter as directly using ...::thread does not (conceptually) scale well.

Generally, it is not possible to directly invoke (most of) HPX's functionality from arbitrary kernel-threads. For this to be possible those threads have to be registered with the runtime. I however admit that the generated error message could be more descriptive. I'll make a note to work on this.

[xaguilar]

Hi, thanks a lot for your explanation. I wasn't aware that blending kernel threads with HPX wasn't a good idea. I needed to sample the counters every certain period and as I already had a thread doing some work at a certain frequency, I just added the code in there. In any case, knowing now that doing this is not good, I'll move all that code to a function used together with hpx::util::interval_time (I wasn't aware either of such HPX utility actually) and I'll remove the additional thread creation. Thanks again!

[RANJEET16520]

Hello Sir, This program shows an error related to it's header file. May be I am not able to compile this program,. I am trying to compile this program from many days but it continuously showing errors. Thanks.

[xaguilar]

Which header file? What errors do you have? I could compile this small example in my environment without any problems.

[hkaiser]

@RANJEET16520 you'll have to be a bit more specific about what errors you're seeing. Also, in order to help we'd need to see the code that causes errors for you (or better, a minimal self-contained example that demonstrates the issue you're seeing).

[RANJEET16520]

Sir this error is shown by header files. I am compiling this code from a week and it still not able to give any output, except this error.

[hkaiser]

@RANJEET16520 You're saying "...except this error". What error specifically? Can you paste it somewhere?