error Too many open files

[xiaoma565]

My codes:

void HttpServer::HandleAccept(std::shared_ptr<ServerConnection> newConnection, const boost::system::error_code& ec)
{
    // Check whether the Server was stopped by a signal before this
    // completion handler had a chance to run.
    if (!acceptor_.is_open()) {
        return;
    }
	if (ec) {
        LOG("[HttpServer] connection accept failed, error is %s\n", ec.what().c_str());
	} else {
        newConnection->Start();
        count_++;
	}
    if (count_ > maxConnections_) {
        std::unique_lock<std::mutex> lock(mtx);
        cv.wait(lock, [this] { return count_ <= maxConnections_; });
    }
	DoAccept();
}

void HttpServer::DoAccept()
{
    auto &ioContext = ioContextPool_.GetIoContext();
    std::shared_ptr<ServerConnection> newConnection = std::make_shared<ServerConnection>(ioContext, reqHandler_, this);
    acceptor_.async_accept(newConnection->GetSocket(), boost::beast::bind_front_handler(&HttpServer::HandleAccept, this,
        newConnection));
}

print so many error:

In my server connection

void ServerConnection::OnRead(boost::beast::error_code ec, std::size_t bytes_transferred)
{
    boost::ignore_unused(bytes_transferred);

    if(ec) {
        LOG("[ServerConnection] OnRead error : %s\n", ec.what().c_str());
        return DoClose();
    }
    keepAlive_ = req_.keep_alive();
    version_ = req_.version();
    auto fun = reqHandler_.GetFun(req_.method(), req_.target());
    if (fun == nullptr) {
        SendNormalRes(boost::beast::http::status::bad_request, "text/plain", "Invalid request\r\n");
    } else {
        fun(shared_from_this()); // 外部记得保存this的指针，防止引用计数到零后释放
    }
    if (keepAlive_) {
        DoRead();
    }
}

void ServerConnection::DoClose()
{
    isClose = true;
    try {
        socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_send);
    } catch (const std::exception& e) {
        LOG("[ServerConnection] DoClose error : %s\n", e.what());
    }
    server_->CloseOne();
}

Is that something wrong with "socket_.shutdown" ?

[xiaoma565]

should I call "socket.close" after "socket.shutdown"?

socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_send);
socket_.close();

[ashtum]

It is hard to tell what could be wrong with the provided code sample. What happens inside server_->CloseOne()? How many active connections do you have? Do they exceed the ulimit -n?

[xiaoma565]

It is hard to tell what could be wrong with the provided code sample. What happens inside server_->CloseOne()? How many active connections do you have? Do they exceed the ulimit -n?

server_->CloseOne() code:

void HttpServer::CloseOne()
{
    if (count_ > maxConnections_) {
        count_--;
        cv.notify_one();
    } else {
        count_--;
    }
}

there are totally 1319 client connections, but i set single thread to accept.
the ulimit -n is 1024.
my io_contextpool is single thread too.
So the process should look something like this: accept -> do something -> close -> accept ...
but why the socket still opening?
I look at /proc/pid/fd with ll | grep socket | wc -l and print 1010.
It seems that socket.close() did not work?

[ashtum]

there are totally 1319 client connections, but i set single thread to accept. the ulimit -n is 1024. my io_contextpool is single thread too. So the process should look something like this: accept -> do something -> close -> accept ... but why the socket still opening? I look at /proc/pid/fd with ll | grep socket | wc -l and print 1010. It seems that socket.close() did not work?

socket.close() should be sufficient. Is your application multi-threaded? What is the purpose of that condition variable, and how does it not block the call to io_context.run()? It is likely you are encountering a concurrency or lifetime bug. I suggest starting with a minimal single-threaded example and then extending it.

[xiaoma565]

there are totally 1319 client connections, but i set single thread to accept. the ulimit -n is 1024. my io_contextpool is single thread too. So the process should look something like this: accept -> do something -> close -> accept ... but why the socket still opening? I look at /proc/pid/fd with ll | grep socket | wc -l and print 1010. It seems that socket.close() did not work?

socket.close() should be sufficient. Is your application multi-threaded? What is the purpose of that condition variable, and how does it not block the call to io_context.run()? It is likely you are encountering a concurrency or lifetime bug. I suggest starting with a minimal single-threaded example and then extending it.

the keypoint

      headerCb = std::bind(&ClientConnection::ParserChunkHeader, self, std::placeholders::_1,
            std::placeholders::_2, std::placeholders::_3);
      bodyCb = std::bind(&ClientConnection::ParserChunkBody, self, std::placeholders::_1,
          std::placeholders::_2, std::placeholders::_3);
      p_->on_chunk_header(headerCb);
      p_->on_chunk_body(bodyCb);

headerCb and bodyCb are ClientConnection's variables, they hold self.

void ClientConnection::Close()
{
    // Send a TCP shutdown
    boost::beast::error_code ec;
    socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec);
    // At this point the connection is closed gracefully
    headerCb = nullptr;
    bodyCb = nullptr;
}

in funcation Close() we should set headerCb and bodyCb to nullptr otherwise the shared_ptr.use_count() will > 0.