Client hangs if it is running in the same process as the server (libiperf)

[BlackPhantomCoder]

Context

Using libiperf I run the client and server in the same process on localhost (in different threads) with the -R flag and at some point the client hangs. (Relatively random, in my example on 1-10 test)

• Version of iperf3: 3.17.1
• Operating system (and distribution, if any): Ubuntu 22.04.1

Bug Report

• Expected Behavior
  Client does not hang

• Actual Behavior
  Client hangs on some test

• Steps to Reproduce
  A simple C++ program to reproduce (iperf_main is main from iperf itself)

void iperf_run(std::vector<std::string> args) {
  args.insert(args.begin(), "iperf"); // program name
  std::vector<char *> varg;
  std::transform(args.begin(), args.end(), std::back_inserter(varg),
                 [](auto &str) { return str.data(); });

  iperf_main(varg.size(), varg.data());
  std::cout << "done" << std::endl;
}

auto launch(std::vector<std::string> args) {
  return std::async(std::launch::async, iperf_run, std::move(args));
}

int main() {
  auto server = launch({"-s"});
  sleep(5);
  for (size_t i = 0; i != 100; ++i) {
    auto client = launch({"-c", "127.0.0.1", "-t", "1", "-R"});
  }
}