zaphoyd
multithreaded websocket++ server crashes
I modified the websocket++ echo server example to use multiple threads:
#include <iostream>
#include <boost/thread/thread.hpp>
#include <websocketpp/config/asio_no_tls.hpp>
#include <websocketpp/server.hpp>
typedef websocketpp::server<websocketpp::config::asio> server;
using websocketpp::lib::placeholders::_1;
using websocketpp::lib::placeholders::_2;
using websocketpp::lib::bind;
// pull out the type of messages sent by our config
typedef server::message_ptr message_ptr;
// Define a callback to handle incoming messages
void on_message(server* s, websocketpp::connection_hdl hdl, message_ptr msg)
{
try {
s->send(hdl, msg->get_payload(), msg->get_opcode());
} catch (const websocketpp::lib::error_code& e) {
std::cout << "Echo failed because: " << e << "(" << e.message() << ")" << std::endl;
}
}
int main()
{
// Create a server endpoint
server echo_server;
boost::asio::io_service io_service;
try {
// Initialize Asio
echo_server.init_asio(&io_service);
// Register our message handler
echo_server.set_message_handler(bind(&on_message, &echo_server, ::_1, ::_2));
// Listen on port 9002
echo_server.set_reuse_addr(true);
echo_server.listen(9002);
// Start the server accept loop
echo_server.start_accept();
boost::thread_group threadpool;
threadpool.create_thread(boost::bind(&boost::asio::io_service::run, &io_service));
threadpool.create_thread(boost::bind(&boost::asio::io_service::run, &io_service));
threadpool.join_all();
} catch (websocketpp::exception const& e) {
std::cout << e.what() << std::endl;
} catch (...) {
std::cout << "other exception" << std::endl;
}
}
I connect using one client which sends many messages asynchronously. Then the server crashes with:
2016-08-31 13:05:44] [info] asio async_read_at_least error: system:125 (Operation canceled)
[2016-08-31 13:05:44] [error] handle_read_frame error: websocketpp.transport:2 (Underlying Transport Error)
terminate called after throwing an instance of 'std::bad_weak_ptr'
what(): bad_weak_ptr
Judging from the websocket++ manual on Thread Safety, what I am doing should be threadsafe:
The Asio transport provides full thread safety for endpoint. Works with an io_service thread pool where multiple threads are calling io_service.run(); ... All core transports guarantee that the handlers for a given connection will be serialized. When the transport and concurrency policies support endpoint concurrency, anything involving a connection_hdl should be thread safe. i.e. It is safe to pass connection_hdls to other threads, store them indefinitely, and call endpoint methods that take them as parameters from any thread at any time.
The client I am using is based on NodeJS:
client.js
var port = 9002;
var times = 10000;
var WebSocket = require("ws");
var ws = new WebSocket("ws://localhost:" + port);
ws.on('open', function open() {
for(var i = 0; i < times; ++i) {
ws.send(i);
}
});
start via:
$ npm install --save ws
$ node client.js
I seem to have run into a similar issue when spawning many async requests from js ws client: namely a bad this pointer in get_message.
Thread 11 "provablyfair_ga" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff1f28700 (LWP 20369)]
websocketpp::message_buffer::alloc::con_msg_managerwebsocketpp::message_buffer::message<websocketpp::message_buffer::alloc::con_msg_manager >::get_message (this=0x0,
op=op@entry=websocketpp::frame::opcode::text, size=141)
at /home/ebola/Projects/ProvablyFair/libprovablyfair/../../websocketpp/websocketpp/message_buffer/alloc.hpp:68
68 return message_ptr(lib::make_shared
#0 0x00000000004aea9d in websocketpp::connectionwebsocketpp::config::asio::send (
op=websocketpp::frame::opcode::text,
payload="{"roll":{"success":true,"nonce":5,"roll":909,"target":1998,"condition_high":true,"amount":1.000000,"profit":-1.000000,"balance":1000.249200}}",
this=0x7fffe40307b0)
at /home/ebola/Projects/ProvablyFair/libprovablyfair/../../websocketpp/websocketpp/impl/connection_impl.hpp:86
#1 websocketpp::endpointwebsocketpp::connection<websocketpp::config::asio, websocketpp::config::asio>::send (ec=
updated to reflect the error on hdl in stack frame 1
The above happens if I create a std::thread backed pool and call send from threads other then the main thread, if I handle all message processing in my on_message handler it has no issues dealing with many async writes.
I also have similar issues. When I move connection_hdl to a thread pool and try to send there sometimes it crashes doesnt seem to have thread safety.
