56a427f839
A request to osrm-routed can be assigned to a thread which is currently busy processing another request, even when there are other threads/cores available. This unnecessarily delays the response, and can make requests appear to hang when awaiting CPU intensive requests to finish. The issue looks like a bug in Boost.Asio multithreaded networking stack. osrm-routed server implementation is heavily influenced by the HTTP server 3 example in the Boost.Asio docs. By upgrading to Boost 1.70 and updating the server connections to match the example provided in the 1.70 release, the problem is resolved. The diff of the changes to the Boost.Asio stack are vast, so it's difficult to identify the exact cause. However the implementation change is to push the strand of execution into the socket (and timer) objects, which suggests it could fix the type of threading issue we are observing.
83 lines
2.3 KiB
C++
83 lines
2.3 KiB
C++
#ifndef CONNECTION_HPP
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#define CONNECTION_HPP
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#include "server/http/compression_type.hpp"
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#include "server/http/reply.hpp"
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#include "server/http/request.hpp"
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#include "server/request_parser.hpp"
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#include <boost/array.hpp>
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#include <boost/asio.hpp>
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#include <boost/config.hpp>
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#include <boost/version.hpp>
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#include <memory>
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#include <vector>
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// workaround for incomplete std::shared_ptr compatibility in old boost versions
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#if BOOST_VERSION < 105300 || defined BOOST_NO_CXX11_SMART_PTR
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namespace boost
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{
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template <class T> const T *get_pointer(std::shared_ptr<T> const &p) { return p.get(); }
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template <class T> T *get_pointer(std::shared_ptr<T> &p) { return p.get(); }
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} // namespace boost
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#endif
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namespace osrm
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{
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namespace server
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{
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class RequestHandler;
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/// Represents a single connection from a client.
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class Connection : public std::enable_shared_from_this<Connection>
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{
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public:
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explicit Connection(boost::asio::io_context &io_context, RequestHandler &handler);
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Connection(const Connection &) = delete;
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Connection &operator=(const Connection &) = delete;
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boost::asio::ip::tcp::socket &socket();
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/// Start the first asynchronous operation for the connection.
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void start();
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private:
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void handle_read(const boost::system::error_code &e, std::size_t bytes_transferred);
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/// Handle completion of a write operation.
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void handle_write(const boost::system::error_code &e);
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/// Handle read timeout
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void handle_timeout(boost::system::error_code);
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void handle_shutdown();
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std::vector<char> compress_buffers(const std::vector<char> &uncompressed_data,
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const http::compression_type compression_type);
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boost::asio::strand<boost::asio::io_context::executor_type> strand;
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boost::asio::ip::tcp::socket TCP_socket;
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boost::asio::deadline_timer timer;
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RequestHandler &request_handler;
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RequestParser request_parser;
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boost::array<char, 8192> incoming_data_buffer;
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http::request current_request;
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http::reply current_reply;
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std::vector<char> compressed_output;
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// Header compression_header;
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std::vector<boost::asio::const_buffer> output_buffer;
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// Keep alive support
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bool keep_alive = false;
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short processed_requests = 512;
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short keepalive_timeout = 5; // In seconds
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};
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} // namespace server
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} // namespace osrm
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#endif // CONNECTION_HPP
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