string copy issue with version 20200708

[YJMLWZ]

hi,
we use pistache 20200708 as HTTP server, when it received a file , let's say the file size is 100MB, we observed the peak memory usage of our app grows rapidly to around 1GB. After checking by valgrind --mass_if, seems pistache copy the file content 8 or 9 times.
want to ask:
is this a known 'issue'?
any refinement regard this in newer version? I see string_view been used but not sure.

[Tachi107]

Hi @YJMLWZ, thanks for the report. Would you be able to identify where and how the big memory usage is happening?

[dennisjenkins75]

8x copies? that is surprising. massif is cool. However, it messes up the threading model. Try heaptrack (I recently started using this, but not with a pistachio project). https://github.com/KDE/heaptrack

[kiplingw]

@YJMLWZ, can you try updating your Pistache to master and let us know if the problem still arises? A lot has changed in the code base since July 2020.

[YJMLWZ]

hi,
after upgrade to version 0.0.3.20220425, situation is much better.
I collected a latest report and pasted below.
I'm using pistache server to receive file from client, file size is around 20MB.

two suggestions:
1, Release the buffer earlier after ParserBase::parse() (http.cc:544) been invoked? not sure whether this is possible.
2, can we avoid the copy of request happened in
route(Pistache::Http::Request const&, Pistache::Http::ResponseWriter) (router.cc:495)
auto req = request;

valgrind mass_if report:
->26.97% (33,554,432B) 0xF4E637: allocate (new_allocator.h:137)
| ->26.97% (33,554,432B) 0xF4E637: allocate (alloc_traits.h:464)
| ->26.97% (33,554,432B) 0xF4E637: _M_allocate (stl_vector.h:378)
| ->26.97% (33,554,432B) 0xF4E637: void std::vector<char, std::allocator >::_M_realloc_insert<char const&>(__gnu_cxx::__normal_iterator<char*, std::vector<char, std::allocator > >, char const&) (vector.tcc:453)
| ->26.97% (33,554,432B) 0x166C87F: push_back (stl_vector.h:1287)
| ->26.97% (33,554,432B) 0x166C87F: operator= (stl_iterator.h:735)
| ->26.97% (33,554,432B) 0x166C87F: __copy_m<char const*, std::back_insert_iterator<std::vector > > (stl_algobase.h:385)
| ->26.97% (33,554,432B) 0x166C87F: __copy_move_a2<false, char const*, std::back_insert_iterator<std::vector > > (stl_algobase.h:495)
| ->26.97% (33,554,432B) 0x166C87F: __copy_move_a1<false, char const*, std::back_insert_iterator<std::vector > > (stl_algobase.h:522)
| ->26.97% (33,554,432B) 0x166C87F: __copy_move_a<false, char const*, std::back_insert_iterator<std::vector > > (stl_algobase.h:529)
| ->26.97% (33,554,432B) 0x166C87F: copy<char const*, std::back_insert_iterator<std::vector > > (stl_algobase.h:620)
| ->26.97% (33,554,432B) 0x166C87F: feed (stream.h:111)
| ->26.97% (33,554,432B) 0x166C87F: feed (stream.h:103)
| ->26.97% (33,554,432B) 0x166C87F: Pistache::Http::Private::ParserBase::feed(char const*, unsigned long) (http.cc:557)
| ->26.97% (33,554,432B) 0x166CFF3: Pistache::Http::Handler::onInput(char const*, unsigned long, std::shared_ptrPistache::Tcp::Peer const&) (http.cc:1076)
| ->26.97% (33,554,432B) 0x1691577: Pistache::Tcp::Transport::handleIncoming(std::shared_ptrPistache::Tcp::Peer const&) (transport.cc:195)
| ->26.97% (33,554,432B) 0x1694BE4: Pistache::Tcp::Transport::onReady(Pistache::Aio::FdSet const&) (transport.cc:103)
| ->26.97% (33,554,432B) 0x16C4378: Pistache::Aio::SyncImpl::handleFds(std::vector<Pistache::Polling::Event, std::allocatorPistache::Polling::Event >) const (reactor.cc:205)
| ->26.97% (33,554,432B) 0x16C465E: Pistache::Aio::SyncImpl::runOnce() (reactor.cc:165)
| ->26.97% (33,554,432B) 0x16C28B9: run (reactor.cc:177)
| ->26.97% (33,554,432B) 0x16C28B9: operator() (reactor.cc:515)
| ->26.97% (33,554,432B) 0x16C28B9: __invoke_impl<void, Pistache::Aio::AsyncImpl::Worker::run()::<lambda()> > (invoke.h:61)
| ->26.97% (33,554,432B) 0x16C28B9: __invoke<Pistache::Aio::AsyncImpl::Worker::run()::<lambda()> > (invoke.h:96)
| ->26.97% (33,554,432B) 0x16C28B9: _M_invoke<0> (std_thread.h:252)
| ->26.97% (33,554,432B) 0x16C28B9: operator() (std_thread.h:259)
| ->26.97% (33,554,432B) 0x16C28B9: std::thread::_State_impl<std::thread::_Invoker<std::tuple<Pistache::Aio::AsyncImpl::Worker::run()::{lambda()
| ->26.97% (33,554,432B) 0xD1E1B42: ??? (in usr/lib64/libstdc++.so.6.0.30)
| ->26.97% (33,554,432B) 0xD4C509B: ??? (in lib64/libc.so.6)
| ->26.97% (33,554,432B) 0xD545CA3: clone (in lib64/libc.so.6)
|
->15.59% (19,392,168B) 0xD251184: std::__cxx11::basic_string<char, std::char_traits, std::allocator >::reserve(unsigned long) (in usr/lib64/libstdc++.so.6.0.30)
| ->15.59% (19,391,142B) 0x1665227: Pistache::Http::Private::BodyStep::parseContentLength(Pistache::StreamCursor&, std::shared_ptrPistache::Http::Header::ContentLength const&) (http.cc:437)
| | ->15.59% (19,391,142B) 0x1666F5C: Pistache::Http::Private::BodyStep::apply(Pistache::StreamCursor&) (http.cc:393)
| | ->15.59% (19,391,142B) 0x1665641: Pistache::Http::Private::ParserBase::parse() (http.cc:544)
| | ->15.59% (19,391,142B) 0x166D014: Pistache::Http::Handler::onInput(char const*, unsigned long, std::shared_ptrPistache::Tcp::Peer const&) (http.cc:1083)
| | ->15.59% (19,391,142B) 0x1691577: Pistache::Tcp::Transport::handleIncoming(std::shared_ptrPistache::Tcp::Peer const&) (transport.cc:195)
| | ->15.59% (19,391,142B) 0x1694BE4: Pistache::Tcp::Transport::onReady(Pistache::Aio::FdSet const&) (transport.cc:103)
| | ->15.59% (19,391,142B) 0x16C4378: Pistache::Aio::SyncImpl::handleFds(std::vector<Pistache::Polling::Event, std::allocatorPistache::Polling::Event >) const (reactor.cc:205)
| | ->15.59% (19,391,142B) 0x16C465E: Pistache::Aio::SyncImpl::runOnce() (reactor.cc:165)
| | ->15.59% (19,391,142B) 0x16C28B9: run (reactor.cc:177)
| | ->15.59% (19,391,142B) 0x16C28B9: operator() (reactor.cc:515)
| | ->15.59% (19,391,142B) 0x16C28B9: __invoke_impl<void, Pistache::Aio::AsyncImpl::Worker::run()::<lambda()> > (invoke.h:61)
| | ->15.59% (19,391,142B) 0x16C28B9: __invoke<Pistache::Aio::AsyncImpl::Worker::run()::<lambda()> > (invoke.h:96)
| | ->15.59% (19,391,142B) 0x16C28B9: _M_invoke<0> (std_thread.h:252)
| | ->15.59% (19,391,142B) 0x16C28B9: operator() (std_thread.h:259)
| | ->15.59% (19,391,142B) 0x16C28B9: std::thread::_State_impl<std::thread::_Invoker<std::tuple<Pistache::Aio::AsyncImpl::Worker::run()::{lambda()
| | ->15.59% (19,391,142B) 0xD1E1B42: ??? (in usr/lib64/libstdc++.so.6.0.30)
| | ->15.59% (19,391,142B) 0xD4C509B: ??? (in lib64/libc.so.6)
| | ->15.59% (19,391,142B) 0xD545CA3: clone (in lib64/libc.so.6)
| |
| ->00.00% (1,026B) in 1+ places, all below ms_print's threshold (01.00%)
|
->15.59% (19,391,296B) 0x16A84FB: void std::__cxx11::basic_string<char, std::char_traits, std::allocator >::_M_construct<char*>(char*, char*, std::forward_iterator_tag) [clone .isra.0] (basic_string.tcc:225)
| ->15.59% (19,391,142B) 0x16B231D: basic_string (basic_string.h:544)
| | ->15.59% (19,391,142B) 0x16B231D: Message (http.h:96)
| | ->15.59% (19,391,142B) 0x16B231D: Pistache::Http::Request::Request(Pistache::Http::Request const&) (http.h:184)
| | ->15.59% (19,391,142B) 0x16AD7EE: Pistache::Rest::Router::route(Pistache::Http::Request const&, Pistache::Http::ResponseWriter) (router.cc:495)
| | ->15.59% (19,391,142B) 0x16AE79D: Pistache::Rest::Private::RouterHandler::onRequest(Pistache::Http::Request const&, Pistache::Http::ResponseWriter) (router.cc:367)
| | ->15.59% (19,391,142B) 0x166D1D7: Pistache::Http::Handler::onInput(char const*, unsigned long, std::shared_ptrPistache::Tcp::Peer const&) (http.cc:1106)
| | ->15.59% (19,391,142B) 0x1691577: Pistache::Tcp::Transport::handleIncoming(std::shared_ptrPistache::Tcp::Peer const&) (transport.cc:195)
| | ->15.59% (19,391,142B) 0x1694BE4: Pistache::Tcp::Transport::onReady(Pistache::Aio::FdSet const&) (transport.cc:103)
| | ->15.59% (19,391,142B) 0x16C4378: Pistache::Aio::SyncImpl::handleFds(std::vector<Pistache::Polling::Event, std::allocatorPistache::Polling::Event >) const (reactor.cc:205)
| | ->15.59% (19,391,142B) 0x16C465E: Pistache::Aio::SyncImpl::runOnce() (reactor.cc:165)
| | ->15.59% (19,391,142B) 0x16C28B9: run (reactor.cc:177)
| | ->15.59% (19,391,142B) 0x16C28B9: operator() (reactor.cc:515)
| | ->15.59% (19,391,142B) 0x16C28B9: __invoke_impl<void, Pistache::Aio::AsyncImpl::Worker::run()::<lambda()> > (invoke.h:61)
| | ->15.59% (19,391,142B) 0x16C28B9: __invoke<Pistache::Aio::AsyncImpl::Worker::run()::<lambda()> > (invoke.h:96)
| | ->15.59% (19,391,142B) 0x16C28B9: _M_invoke<0> (std_thread.h:252)
| | ->15.59% (19,391,142B) 0x16C28B9: operator() (std_thread.h:259)
| | ->15.59% (19,391,142B) 0x16C28B9: std::thread::_State_impl<std::thread::_Invoker<std::tuple<Pistache::Aio::AsyncImpl::Worker::run()::{lambda()
| | ->15.59% (19,391,142B) 0xD1E1B42: ??? (in usr/lib64/libstdc++.so.6.0.30)
| | ->15.59% (19,391,142B) 0xD4C509B: ??? (in lib64/libc.so.6)
| | ->15.59% (19,391,142B) 0xD545CA3: clone (in lib64/libc.so.6)

[YJMLWZ]

@kiplingw @Tachi107