http async response handling with pistache framework - c++

Question

I am trying to write a c++ pistache server that, on a specific endpoint, has to contact another pistache server.
This is the scenario:
client -> server1 -> server2
client <- server1 <- server2
I am having problems waiting for the response in server1 and sending it back to the client asynchronously.
More in details:
I think that an efficient way of handling this problem should be to call the response.send in the resp.then block (it returns a Pistache::Async::Promise). Unluckily, it gives a segmentation fault once that endpoint is called and it gets in the then block. So I guess it is illegal to do that as I wanted. Also, the logs are not giving more details than segmentation fault, so it is hard to debug.
I share my server1 code to show you how I did implement it.
void doSmth(const Rest::Request& request, Http::ResponseWriter httpResponse)
{
auto resp_srv2 = client
.post(addr)
.body(json)
.send();
resp_srv2.then(
[&](Http::Response response) {
httpResponse.send(r.response_code);
},
[&](std::exception_ptr exc) {
PrintException excPrinter;
excPrinter(exc);
});
}
In this case, I could avoid using the barrier as shown in the pistache git repo. Using their code, 28k requests from the user are correctly handled, and then I guess that the resources are not correctly allocated since it gets stuck.
Do you know how to send the response to the client once received the server2 response asynchronously? I need to do it in an optimized way and correctly allocate all the resources.
Thanks for your help!