我观察到从 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）时性能急剧下降（CPU 消耗急剧增加） . 毫无疑问我做错了什么，但我无法想象是什么。
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，我还必须进行大量 API 更改。例如：
req.fields.replace(hdrName, hdrValue);
就是现在：
req.set(hdrName, hdrValue);
该应用程序工作正常——包括 SSL 握手和代理协商——但我必须解决 CPU 消耗的峰值和相应的性能下降。我想知道是否有人知道我忽略的一些明显的事情。
编辑：我应该提到我正在为 SSL 流使用 flat_buffer。
我有机会分析“端口前”和“端口后”的性能数据。这是“端口前”（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“端口后”（即性能不佳）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