[boost asio interaction] Restarting an io_service

[niekbouman]

Hi,

I am using the Boost.Fiber <-> Boost.Asio coupling via the boost::fibers::asio::round_robin scheduler, and I am trying to relaunch an asio io_service, that has previously been stopped.

The problem is, that the scheduler (or fiber) hangs after the second execution of the .run() method.
In the code example below, the "this line is never reached\n" string is never printed.

#include <iostream>
#include <boost/asio/io_context.hpp>
#include "round_robin.hpp"
#include <boost/fiber/all.hpp>

using io_context_ptr = std::shared_ptr<boost::asio::io_service>;

void start(io_context_ptr io_ctx)
{

  boost::asio::system_timer t(*io_ctx);
  t.expires_after(std::chrono::seconds(1));
  t.async_wait(boost::fibers::asio::yield);

  io_ctx->stop();

}

int main()
{
    io_context_ptr io_ctx = std::make_shared<boost::asio::io_service>();
    boost::fibers::use_scheduling_algorithm<boost::fibers::asio::round_robin>(io_ctx);
    auto f = boost::fibers::fiber(start, io_ctx);
    io_ctx->run();
    f.join();

    std::cout << "foo\n";

    io_ctx->restart();
    auto f2 = boost::fibers::fiber(start, io_ctx);

    std::cout << "bar\n";
    
    io_ctx->run();
    std::cout << "this line is never reached\n";
    f2.join();

}

[jpcordovae]

if I remember well you have to reset your service before restart it (there is a restart function btw). I suggest to carefully read the documentation, sometimes functions names are misinterpreted or require a context not so evident.

https://stackoverflow.com/questions/15568100/confused-when-boostasioio-service-run-method-blocks-unblocks