NIO+Multithreaded TCPSocket listener, very low cpu utilisation

[kdevel]

On Thursday, 16 November 2017 at 19:37:31 UTC, ade90036 wrote:
> Can we enable some sort of profiling to see what is going on?

You may compile the code with dmd -g -O -profile -profile=gc

I currently struggle getting meaningful output. I want to 
terminate the program after a number (say 400) handled requests. 
When returning from main the program hangs, so I call exit.

The running binary now produces a trace.log but even after 
wrapping
new SocketSet(); into

```
auto socket_set_allocation_wrapper ()
{
    writeln (__FUNCTION__);
    return new SocketSet();
}
```

I see the invocations in handle_socket in the console but not in 
trace.log.