我正在使用我配置的多线程websocketpp服务器：
Server::Server(int ep) {
using websocketpp::lib::placeholders::_1;
using websocketpp::lib::placeholders::_2;
using websocketpp::lib::bind;
Server::wspp_server.clear_access_channels(websocketpp::log::alevel::all);
Server::wspp_server.init_asio();
Server::wspp_server.set_open_handler(bind(&Server::on_open, this, _1));;
Server::wspp_server.set_close_handler(bind(&Server::on_close, this, _1));
Server::wspp_server.set_message_handler(bind(&Server::on_message, this, _1, _2));
try {
Server::wspp_server.listen(ep);
} catch (const websocketpp::exception &e){
std::cout << "Error in Server::Server(int): " << e.what() << std::endl;
}
Server::wspp_server.start_accept();
}
void Server::run(int threadCount) {
boost::thread_group tg;
for (int i = 0; i < threadCount; i++) {
tg.add_thread(new boost::thread(
&websocketpp::server<websocketpp::config::asio>::run,
&Server::wspp_server));
std::cout << "Spawning thread " << (i + 1) << std::endl;
}
tg.join_all();
}
void Server::updateClients() {
/*
run updates
*/
for (websocketpp::connection_hdl hdl : Server::conns) {
try {
std::string message = "personalized message for this client from the ran update above";
wspp_server.send(hdl, message, websocketpp::frame::opcode::text);
} catch (const websocketpp::exception &e) {
std::cout << "Error in Server::updateClients(): " << e.what() << std::endl;
}
}
}
void Server::on_open(websocketpp::connection_hdl hdl) {
boost::lock_guard<boost::shared_mutex> lock(Server::conns_mutex);
Server::conns.insert(hdl);
//do stuff
//when the first client connects, start the update routine
if (conns.size() == 1) {
Server::run = true;
bool *run = &(Server::run);
std::thread([run] () {
while (*run) {
auto nextTime = std::chrono::steady_clock::now() + std::chrono::milliseconds(15);
Server::updateClients();
std::this_thread::sleep_until(nextTime);
}
}).detach();
}
}
void Server::on_close(websocketpp::connection_hdl hdl) {
boost::lock_guard<boost::shared_mutex> lock(Server::conns_mutex);
Server::conns.erase(hdl);
//do stuff
//stop the update loop when all clients are gone
if (conns.size() < 1)
Server::run = false;
}
void Server::on_message(
websocketpp::connection_hdl hdl,
websocketpp::server<websocketpp::config::asio>::message_ptr msg) {
boost::lock_guard<boost::shared_mutex> lock(Server::conns_mutex);
//do stuff
}
我用：
启动服务器int port = 9000;
Server server(port);
server.run(/* number of threads */);
添加连接时唯一重要的区别在于消息发送[wssp.send(...)]。越来越多的客户并没有真正为内部计算添加任何东西。它只是增加的消息量。
我的问题是，无论我使用一个还是多个线程，CPU使用率似乎都没那么大。
使用server.run(1)或server.run(4)（均在4核CPU专用服务器上）启动服务器并不重要。对于类似的负载，CPU使用率图表显示大致相同的百分比。我希望4个线程并行运行时使用率会降低。我想错了吗？
在某些时候，我感觉到并行性确实适用于听力部分而不是发射。因此，我尝试将send括在一个新线程中（我将其分离），因此它独立于需要它的序列，但它并没有改变图形上的任何内容。
我不应该看到CPU产生的工作有什么不同吗？否则，我做错了什么？为了强制从不同的线程发出消息，我还缺少另一个步骤吗？
答案 0 :(得分：1)
"My problem is that the CPU usage doesn't seem to be that much different whether I use 1 or more threads."
That's not a problem. That's a fact. It just means that the whole thing isn't CPU bound. Which should be quite obvious, since it's network IO. In fact, high-performance servers often dedicate only 1 thread to all IO tasks, for this reason.
"I was expecting the usage to be lower with 4 threads running in parallel. Am I thinking of this the wrong way?"
Yes, it seems to. You don't expect to pay less if you split the bill 4 ways either.
In fact, much like at the diner, you often end up paying more due the overhead of splitting the load (cost/tasks). Unless you require more CPU capacity/lower reaction times than a single thread can deliver, a single IO thread is (obviously) more efficient because there is no scheduling overhead and/or context switch penalty.
Another mental exercise: