Hello, I am working on a simple utility which scans an IP range and performs a reverse lookup. Using ASIO, I would like to use async_resolve to accomplish this. However, it seems that when using async_resolve() with an ::endpoint overload, the call is blocking. I am wrapping all async functions in a strand and calling io_service::run() from multiple threads. Here is an example: ------------------------------------------------------------------- class client { public: client ( boost::asio::io_service & io_service ) : io_service_(io_service), resolver_(io_service), strand_(io_service) { /* */ } void resolve_host ( const std::string & host ) { strand_.post( boost::bind(&client::start_resolve, this, host ) ); } void start_resolve ( const std::string & host_ ) { //boost::asio::ip::tcp::resolver::query query( tcp::v4(), host_, "" ); tcp::endpoint endpoint ( boost::asio::ip::address::from_string( host_) , 0 ); resolver_.async_resolve( endpoint, strand_.wrap( boost::bind( &client::handle_resolve, this, boost::asio::placeholders::error, boost::asio::placeholders::iterator ) ) ); } void handle_resolve ( const boost::system::error_code& err, tcp::resolver::iterator endpoint_iterator ) { if ( !err ) { /* attempt to connect */ tcp::endpoint endpoint = *endpoint_iterator; cout << endpoint.address() << "' >> " << (*endpoint_iterator).host_name() << endl; } } private: tcp::resolver resolver_; boost::asio::strand strand_; boost::asio::io_service & io_service_; }; int main( int argc, char* argv[] ) { /* io service */ boost::asio::io_service io_service; /* ip range */ std::string m_addr = "10.1.10."; /* client object */ boost::shared_ptr<client> m_client ( new client ( io_service ) ); /* add the entire subnet */ for ( int i=1; i<255; i++ ) { m_client->resolve_host ( m_addr + boost::to_string(i) ); } /* create threads and run io_service */ std::vector < boost::shared_ptrboost::thread > m_threads; for ( int i=0; i < CPU_CORES; i++ ) { m_threads.push_back ( boost::shared_ptrboost::thread ( new boost::thread(boost::bind(&boost::asio::io_service::run, &io_service ) ) ) ); } for ( int i=0; i < CPU_CORES; i++ ) { m_threads[i]->join(); } return 0; } ------------------------------------------------------ I am looking for suggestions on how I can take a multi-threaded approach to this. I am fairly new to ASIO so I appreciate any advice! Thanks -- Kyle Ketterer