Re: [Boost-users] [asio] Second connection fails

Subject: Re: [Boost-users] [asio] Second connection fails
From: William Jagels (william_at_[hidden])
Date: 2018-06-21 03:01:05

Can you re-run your test code with handler tracking enabled and post the
output? How to enable:
https://www.boost.org/doc/libs/1_67_0/doc/html/boost_asio/overview/core/handler_tracking.html

On Tue, Jun 19, 2018, 07:16 Florian Lindner via Boost-users <
boost-users_at_[hidden]> wrote:

> Hello,
>
> I am using boost.asio to connect a self written host. The function below
> is called with acceptorRanks = {0, 1}. The
> first connection went well, but the second one fails (to 1). It is always
> the second with, e.g. when called with {1, 0},
> connecting to 0 fails.
>
> I took the code out of context, changed some lines for clarity, I hope you
> can help me!
>
> The sockets seems to connect, i.e. there is no error, but the asio::write
> fails with "Bad file descriptor"
>
> Wireshark only shows traffic for the first connections, nothing at all the
> second (when filtered by port name). The
> connection is always on localhost.
>
> The host to wich I connect always takes on connection per process, that is
> way I think the problem is with the requester.
>
> I would be really thankful for any help what the problem could be.
>
> Best Thanks!
> Florian
>
>
> Same code: https://gist.github.com/floli/d418405ca50d722f1abf8bf5971466e2
>
> void requestConnection(std::string      const &nameAcceptor,
>                        std::string      const &nameRequester,
>                        std::set<int>    const &acceptorRanks,
>                        int                     requesterRank)
>
> {
>   boost::asio::ip::tcp::resolver resolver(*_ioService);
>
>   for (auto const & acceptorRank : acceptorRanks) {
>     try {
>       address = readAddress(nameAcceptor, nameRequester, acceptorRank);
>       DEBUG("Requesting connection to " << address);
>
>       std::string ipAddress  = address.substr(0, address.find(":"));
>       std::string portNumber = address.substr(ipAddress.length()+1,
> address.length() - ipAddress.length()-1);
>
>       _portNumber = static_cast<unsigned short>(std::stoi(portNumber));
>
>       PtrSocket socket(new Socket(*_ioService)); // shared_ptr to socket
>
>       using asio::ip::tcp;
>
>       tcp::resolver::query query(tcp::v4(), ipAddress, portNumber);
>
>       while (not isConnected()) {
>         tcp::resolver::iterator endpoint_iterator =
> resolver.resolve(query);
>         boost::system::error_code error = asio::error::host_not_found;
>         boost::asio::connect(*socket, endpoint_iterator, error);
>
>         _isConnected = not error;
>
>         if (not isConnected()) {
>           // Wait a little, since after a couple of ten-thousand trials
> the system
>           // seems to get confused and the requester connects wrongly to
> itself.
>           boost::asio::deadline_timer timer(*_ioService,
> boost::posix_time::milliseconds(1));
>           timer.wait();
>         }
>       }
>
>       DEBUG("Requested connection to " << address << ", rank = " <<
> acceptorRank);
>       _sockets[acceptorRank] = socket;
>       WARN("CHECKPOINT 1 FOR RANK " << acceptorRank);
>       asio::write(*_sockets.at(acceptorRank),
> asio::buffer(&requesterRank, sizeof(int)));
>       WARN("CHECKPOINT 2 FOR RANK " << acceptorRank); // reached only for
> acceptorRank=0
>     } catch (std::exception &e) {
>       ERROR("Requesting connection to " << address << " failed: " <<
> e.what());
>     }
>   }
>   // NOTE:
>   // Keep IO service running so that it fires asynchronous handlers from
> another thread.
>   _work   = PtrWork(new asio::io_service::work(*_ioService));
>   _thread = std::thread([this]() { _ioService->run(); });
> }
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