端口性能从Beast.1.0.0-b66降到Boost.1.67.0.Beast

Question

从Beast.1.0.0-b66（使用Boost.1.64.0）迁移到Boost.1.67.0.Beast（即将Beast集成到Boost中）后，我观察到性能急剧下降（CPU消耗急剧增加）。 。毫无疑问，我做错了什么，但我无法想象。

什么是：

typedef beast::http::request<beast::http::string_body> BeastHttpRequest;

就是现在：

namespace http = boost::beast::http;    
typedef http::request<http::string_body> BeastHttpRequest;

什么是：

beast::http::prepare(req);
beast::http::write(stream, req);

就是现在：

req.prepare_payload();
http::write(stream, req);

当然，我还必须进行许多API更改。例如：

req.fields.replace(hdrName, hdrValue);

就是现在：

req.set(hdrName, hdrValue);

该应用程序可以正常工作-包括SSL握手和代理协商-但我必须解决CPU消耗高峰和性能相应下降的问题。我想知道是否有人知道我忽略了一些明显的事情。

编辑：我应该提到我正在为SSL流使用flat_buffer。

我有机会分析“端口之前”和“端口之后”性能数据。这是“端口之前”（即良好的性能）调用链：

- 34.61% HttpRequest::send
   - 32.02% beast::http::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&>, true, beast::http::string_body,
      - 31.90% beast::http::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&>, true, beast::http::string_bo
         - 20.77% beast::http::detail::write_preparation<true, beast::http::string_body, beast::http::basic_fields<std::allocator<char> > >::init
            - 18.25% beast::http::detail::write_fields<beast::basic_streambuf<std::allocator<char> >, beast::http::basic_fields<std::allocator<char> > >
               - 10.38% beast::write<beast::basic_streambuf<std::allocator<char> >, boost::basic_string_ref<char, std::char_traits<char> > >
                  - 10.20% beast::detail::write_dynabuf<beast::basic_streambuf<std::allocator<char> >, boost::basic_string_ref<char, std::char_traits<char> > >
                     + 3.66% beast::basic_streambuf<std::allocator<char> >::prepare
                     + 2.90% beast::basic_streambuf<std::allocator<char> >::commit
                     + 1.81% boost::lexical_cast<std::string, boost::basic_string_ref<char, std::char_traits<char> > >
                     + 1.47% boost::asio::buffer_copy<beast::basic_streambuf<std::allocator<char> >::mutable_buffers_type>
               - 7.51% beast::write<beast::basic_streambuf<std::allocator<char> >, char [3]>
                  - 7.47% beast::detail::write_dynabuf<beast::basic_streambuf<std::allocator<char> >, 3ul>
                     + 3.14% beast::basic_streambuf<std::allocator<char> >::prepare
                     + 2.84% beast::basic_streambuf<std::allocator<char> >::commit
                     + 1.32% boost::asio::buffer_copy<beast::basic_streambuf<std::allocator<char> >::mutable_buffers_type>
            + 2.04% beast::http::detail::write_start_line<beast::basic_streambuf<std::allocator<char> >, beast::http::basic_fields<std::allocator<char> > >
         - 9.60% beast::http::string_body::writer::write<beast::http::detail::writef0_lambda<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_serv
            - 9.57% beast::http::detail::writef0_lambda<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&>, beast:
               - 9.54% boost::asio::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&>, beast::detail::buffe
                  - 9.48% boost::asio::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&>, beast::detail::bu
                     - 8.55% boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >&>::write_some<boost::asio::detail::c
                        - 7.56% boost::asio::ssl::detail::io<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, boost::asio::ssl::detail::wr
                           - 6.98% boost::asio::write<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, boost::asio::mutable_buffers_1>
                              - 6.93% boost::asio::write<boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >, boost::asio::mutable_buffers_1,
                                 - 6.69% boost::asio::basic_stream_socket<boost::asio::ip::tcp, boost::asio::stream_socket_service<boost::asio::ip::tcp> >::write_some<boost::asio::detail::consuming_buffer
                                    - 6.69% boost::asio::stream_socket_service<boost::asio::ip::tcp>::send<boost::asio::detail::consuming_buffers<boost::asio::const_buffer, boost::asio::mutable_buffers_1>
                                       - 6.67% boost::asio::detail::reactive_socket_service_base::send<boost::asio::detail::consuming_buffers<boost::asio::const_buffer, boost::asio::mutable_buffers_1> >
                                          - 6.51% boost::asio::detail::socket_ops::sync_send
                                             - 6.32% 0xec6d
                                                - 6.08% system_call_fastpath
                                                   - 6.07% sys_sendmsg
                                                      - 6.06% __sys_sendmsg
                                                         - 5.94% ___sys_sendmsg
                                                            + 5.84% sock_send

这是“后端口”（即性能较差）调用链：

- 53.77% HttpRequest::send
   - 53.32% boost::beast::http::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&>, true, boost::beast::http::basic_string_body<char, std::char_traits<char>, std::allo
      - 53.30% boost::beast::http::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&>, true, boost::beast::http::basic_string_body<char, std::char_traits<char>, std::a
         - 53.14% boost::beast::http::write<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&>, true, boost::beast::http::basic_string_body<char, std::char_traits<char>, std
            - 53.03% boost::beast::http::write_some<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&>, true, boost::beast::http::basic_string_body<char, std::char_traits<ch
               - 52.95% boost::beast::http::detail::write_some_impl<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&>, true, boost::beast::http::basic_string_body<char, std
                  - 36.58% boost::beast::http::serializer<true, boost::beast::http::basic_string_body<char, std::char_traits<char>, std::allocator<char> >, boost::beast::http::basic_fields<std::allocator<
                     - 35.28% boost::beast::http::serializer<true, boost::beast::http::basic_string_body<char, std::char_traits<char>, std::allocator<char> >, boost::beast::http::basic_fields<std::allocat
                        - 25.93% boost::beast::http::detail::write_some_lambda<boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&> >::operator()<boost::beast::detail::buffers
                           - 25.82% boost::asio::ssl::stream<boost::asio::basic_stream_socket<boost::asio::ip::tcp>&>::write_some<boost::beast::detail::buffers_ref<boost::beast::buffers_prefix_view<boost:
                              - 25.69% boost::asio::ssl::detail::io<boost::asio::basic_stream_socket<boost::asio::ip::tcp>, boost::asio::ssl::detail::write_op<boost::beast::detail::buffers_ref<boost::beas
                                 - 22.20% boost::asio::write<boost::asio::basic_stream_socket<boost::asio::ip::tcp>, boost::asio::mutable_buffer>
                                    - 22.13% boost::asio::write<boost::asio::basic_stream_socket<boost::asio::ip::tcp>, boost::asio::mutable_buffer, boost::asio::detail::transfer_all_t>
                                       - 21.96% boost::asio::detail::write_buffer_sequence<boost::asio::basic_stream_socket<boost::asio::ip::tcp>, boost::asio::mutable_buffer, boost::asio::mutable_buffer
                                          - 21.47% boost::asio::basic_stream_socket<boost::asio::ip::tcp>::write_some<boost::asio::const_buffers_1>
                                             - 21.34% boost::asio::detail::reactive_socket_service_base::send<boost::asio::const_buffers_1>
                                                - 21.17% boost::asio::detail::socket_ops::sync_send
                                                   - 20.45% 0xec6d
                                                      - 19.63% system_call_fastpath
                                                         - 19.57% sys_sendmsg
                                                            - 19.52% __sys_sendmsg
                                                               - 19.16% ___sys_sendmsg
                                                                  + 18.90% sock_sendmsg

Answer 1

随着HTTP算法的优化，它应该更快而不是更慢。我想我知道发生了什么事。如果可以在使用常规套接字而不是SSL时比较两个版本的性能，将很有帮助。boost::asio::ssl::stream有一个缺点是，当写入长度大于1的缓冲区序列时，它会为序列中的每个缓冲区写入套接字，而不是将那些加密的缓冲区合并为一个写入。这可能会对性能产生重大影响。

这确实需要在Boost.Asio中修复，但是一种解决方法是您可以编写自己的流包装器，其写算法在出现长度大于1的缓冲区序列时会通过使用memcpy和动态分配来创建长度为1的新序列。。我还会在这里打开一个问题：https : //github.com/boostorg/asio/issues

为什么Beast的两个版本有所不同？较早版本的Beast在序列化过程中分配了内存以保存消息的线性版本。当前版本使用的算法根本不需要内存分配。在通常情况下，它速度更快，但是正如您在使用ssl::stream类型时发现的那样，它可能会更慢。

参见https://github.com/boostorg/beast/issues/1108