Question about the coordinator in sources and why it causes segfault about rxcpp

[wuyuanyi135]

from my observation, the following case will also fail:
Does it mean I should not use coordinator in the source anywhere?

  std::vector<int> data{1, 2, 3, 4, 5};
  schedulers::run_loop rl;
  identity_one_worker c(schedulers::make_run_loop(rl));
  sources::iterate(data, c)
      .tap([](auto _) {std::cout << "before delay\n";})
      .delay(std::chrono::milliseconds(500))
      .tap([](auto _) {std::cout << "after delay\n";})
      .subscribe([](int v) {
        std::cout << "Next " << v << "\n";
      });

[wuyuanyi135]

I started investigating this issue. I found that the crash was caused by the following line.

RxCpp/Rx/v2/src/rxcpp/rx-scheduler.hpp

Line 349 in 761b932

return worker(lifetime, inner.lock());

For some reason, the weak_ptr returned NULL, presumably the underlying shared pointer has been released somehow.

[wuyuanyi135]

One possibility is that the sources (like just or iterate) uses identity_immediate coordinator by default:

RxCpp/Rx/v2/src/rxcpp/sources/rx-iterate.hpp

Line 277 in 761b932

decltype(iterate(std::declval<std::array<rxu::decay_t<Value0>, 1>>(), identity_immediate()))>::type {

This makes more sense to me as emitting values does not sounds like asynchronous operation (except interval). Passing the runloop coordinator seems not a good choice but why will it crash?

[kirkshoop]

Can you add the stack for the crash?

[wuyuanyi135]

@kirkshoop Sorry for the late response. Here is the stack: (I am using master branch of rxcpp)

rxcpp::schedulers::worker::schedule_rebind<…>(const rxcpp::schedulers::schedulable &) const rx-scheduler.hpp:815
rxcpp::schedulers::worker::schedule rx-scheduler.hpp:260
rxcpp::schedulers::schedulable::schedule rx-scheduler.hpp:621
rxcpp::schedulers::detail::action_tailrecurser::operator() rx-scheduler.hpp:715
std::__invoke_impl<…> invoke.h:61
std::__invoke_r<…> invoke.h:111
std::_Function_handler::_M_invoke(const std::_Any_data &, const rxcpp::schedulers::schedulable &, const rxcpp::schedulers::recurse &) std_function.h:291
std::function::operator()(const rxcpp::schedulers::schedulable &, const rxcpp::schedulers::recurse &) const std_function.h:560
rxcpp::schedulers::detail::action_type::operator() rx-scheduler.hpp:679
rxcpp::schedulers::action::operator() rx-scheduler.hpp:727
rxcpp::schedulers::schedulable::operator() rx-scheduler.hpp:645
rxcpp::schedulers::run_loop::dispatch rx-runloop.hpp:192
main emitting_a_list_simultaneously_or_sequentially.cpp:37
__tmainCRTStartup 0x00007ff72cc9143f
mainCRTStartup 0x00007ff72cc91146
BaseThreadInitThunk 0x00007ff8045554e0
RtlUserThreadStart 0x00007ff8049a485b
<unknown> 0x0000000000000000