Can you prepare a little (or large) test case, so that I can debug
locally? I think exit code -11 indicates a segmentation fault.
https://github.com/atilaneves/mqtt
Add "enableWorkerThreads()" and TCPListenOptions.distribute to mqttd/app.d, "dub" to run it then "telnet localhost 1883" with any input reproduces the problem. Comment out "enableWorkerThreads" and the app complains about an invalid message instead (since telnet isn't sending anything meaningful) and carries on. Put it back in and the complaint is still there but it exits soon thereafter.
Atila