beast: Getting "partial message" error on http_client_async

Hi,

I modified the example code in http_client_async to create multiple sessions and download multiple files.

So on main(), I did something like:

// Launch the asynchronous operation
for (int n=0; n<10; ++n)
{
  std::ostringstream os;
  os << target
     << "test"
     << n+1
     << "_20M.csv";
  std::make_shared<session>(ioc)->run(host, port, os.str().c_str(), version);
}

Each one of the sessions then start to download “some_target/testN_20M.csv”. However, some, if not all, of the sessions end with an error: “read: partial message”. Hope you can help.