Memory leak when executor is not executed

[kone-tlammi]

Issue

I was writing unit tests and hit address sanitizer memory leak issues.

Minimal code to reproduce the issue:

#include <boost/asio.hpp>
#include <boost/cobalt.hpp>
#include <print>

namespace cobalt = boost::cobalt;
namespace asio = boost::asio;

cobalt::task<void> tsk() {
  std::println("Hello, World!");
  co_return;
}

int main() {
  auto ioc = asio::io_context();
  cobalt::spawn(ioc.get_executor(), tsk(), boost::asio::detached);
}

I get the leak detection with commands

g++ -std=c++23 -fsanitize=address ./main.cpp -lboost_cobalt
clang++ -std=c++23 -fsanitize=address ./main.cpp -lboost_cobalt
clang++ -std=c++23 -fsanitize=leak ./main.cpp -lboost_cobalt

g++'s leak detector does not report anything.

When modifying the code a bit I can see a growing trend in memory usage using pmap -x:

#include <boost/asio.hpp>
#include <boost/cobalt.hpp>
#include <print>

namespace cobalt = boost::cobalt;
namespace asio = boost::asio;
using namespace std::literals;

cobalt::task<void> tsk() {
  std::println("Hello, World!");
  co_return;
}

int main() {
  while (true) {
    auto ioc = asio::io_context();
    cobalt::spawn(ioc.get_executor(), tsk(), boost::asio::detached);
    std::this_thread::sleep_for(10ms);
  }
}

System Information:

• g++ version: 14.2.1
• clang++ version: 19.1.7
• boost version: 1.87.0-3
  • Checked also with boost-cobalt's HEAD
• OS: Manjaro Linux

Asan trace

Indirect leak of 352 byte(s) in 1 object(s) allocated from:
    #0 0x7f3a331b697a in operator new(unsigned long, std::align_val_t) /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_new_delete.cpp:107
    #1 0x5576d91ca2ad in std::pmr::memory_resource::allocate(unsigned long, unsigned long) /usr/include/c++/14.2.1/bits/memory_resource.h:76
    #2 0x5576d92118cc in std::pmr::polymorphic_allocator<max_align_t>::allocate(unsigned long) /usr/include/c++/14.2.1/bits/memory_resource.h:162
    #3 0x5576d920eec1 in std::allocator_traits<std::pmr::polymorphic_allocator<max_align_t> >::allocate(std::pmr::polymorphic_allocator<max_align_t>&, unsigned long) /usr/include/c++/14.2.1/bits/memory_resource.h:452
    #4 0x5576d920d1eb in void* boost::cobalt::allocate_coroutine<std::pmr::polymorphic_allocator<void> >(unsigned long, std::pmr::polymorphic_allocator<void>) /usr/include/boost/cobalt/this_coro.hpp:412
    #5 0x5576d9209758 in void* boost::cobalt::detail::partial_promise_base<std::pmr::polymorphic_allocator<void> >::operator new<boost::cobalt::detail::async_initiate_spawn::operator()<boost::asio::detail::detached_handler>(boost::asio::detail::detached_handler&&, boost::cobalt::task<void>)::completion_handler>(unsigned long, boost::asio::detail::detached_handler&) /usr/include/boost/cobalt/detail/wrapper.hpp:33
    #6 0x5576d9205e5b in std::__n4861::coroutine_handle<boost::cobalt::detail::post_coroutine_promise<boost::asio::associated_allocator<boost::cobalt::detail::async_initiate_spawn::operator()<boost::asio::detail::detached_handler>(boost::asio::detail::detached_handler&&, boost::cobalt::task<void>)::completion_handler, std::allocator<void> >::type> > boost::cobalt::detail::post_coroutine<boost::cobalt::detail::async_initiate_spawn::operator()<boost::asio::detail::detached_handler>(boost::asio::detail::detached_handler&&, boost::cobalt::task<void>)::completion_handler>(boost::cobalt::detail::async_initiate_spawn::operator()<boost::asio::detail::detached_handler>(boost::asio::detail::detached_handler&&, boost::cobalt::task<void>)::completion_handler) /usr/include/boost/cobalt/detail/wrapper.hpp:145
    #7 0x5576d9200448 in void boost::cobalt::detail::async_initiate_spawn::operator()<boost::asio::detail::detached_handler>(boost::asio::detail::detached_handler&&, boost::cobalt::task<void>) /usr/include/boost/cobalt/detail/spawn.hpp:156
    #8 0x5576d91f9738 in void boost::asio::async_result<boost::asio::detached_t, void (std::__exception_ptr::exception_ptr)>::initiate<boost::cobalt::detail::async_initiate_spawn, boost::asio::detached_t const&, boost::cobalt::task<void> >(boost::cobalt::detail::async_initiate_spawn&&, boost::asio::detached_t const&, boost::cobalt::task<void>&&) /usr/include/boost/asio/impl/detached.hpp:66
    #9 0x5576d91ed427 in decltype (std::enable_if<std::enable_if<boost::asio::detail::are_completion_signatures<void (std::__exception_ptr::exception_ptr)>::value, boost::asio::detail::async_result_has_initiate_memfn<boost::asio::detached_t const&, void (std::__exception_ptr::exception_ptr)> >::type::value, boost::asio::async_result<std::decay<boost::asio::detached_t const&>::type, void (std::__exception_ptr::exception_ptr)> >::type::initiate(static_cast<boost::cobalt::detail::async_initiate_spawn&&>({parm#1}), static_cast<boost::asio::detached_t const&>({parm#2}), static_cast<boost::cobalt::task<void>&&>({parm#3}))) boost::asio::async_initiate<boost::asio::detached_t const&, void (std::__exception_ptr::exception_ptr), boost::cobalt::detail::async_initiate_spawn, boost::cobalt::task<void> >(boost::cobalt::detail::async_initiate_spawn&&, boost::asio::type_identity<boost::asio::detached_t const&>::type&, boost::cobalt::task<void>&&) /usr/include/boost/asio/async_result.hpp:629
    #10 0x5576d91e1bca in auto boost::cobalt::spawn<boost::asio::io_context::basic_executor_type<std::allocator<void>, 0ul>, boost::asio::detached_t const&>(boost::asio::io_context::basic_executor_type<std::allocator<void>, 0ul>, boost::cobalt::task<void>&&, boost::asio::detached_t const&) /usr/include/boost/cobalt/spawn.hpp:46
    #11 0x5576d91c563e in main main.cpp:15
    #12 0x7f3a32b18487  (/usr/lib/libc.so.6+0x27487) (BuildId: 0b707b217b15b106c25fe51df3724b25848310c0)
    #13 0x7f3a32b1854b in __libc_start_main (/usr/lib/libc.so.6+0x2754b) (BuildId: 0b707b217b15b106c25fe51df3724b25848310c0)
    #14 0x5576d91c4a74 in _start (/home/user/code/tmp/memleak+0x14a74) (BuildId: 0df25372cad66ca46b7a5c0ac6822af7420d841a)