Server crash under heavy load

[andreynech]

Hi Folks,

I am evaluating hbmqtt for the kind of video streaming scenario where I am publishing mjpeg (sequence of jpegs) with 30-60 FPS rate. For test purposes I have created the following publisher using paho client: https://github.com/veter-team/mechspeak/blob/master/src/publish2.py . It publishes all jpeg files found in the directory specified by the frames_dir variable at the beginning of the file. Subscribers are simple web-applications also written with paho js client. They receive jpegs and displays it on the canvas. Relevant sources are:
https://github.com/veter-team/mechspeak/blob/master/www/videoobserver.html
https://github.com/veter-team/mechspeak/blob/master/www/js/utility.js

I was running the following configurations:

1. hbmqtt and publish2.py running on raspberry pi 2 connected to the network over Ethernet. Three web-subscribers (browser windows) running on other machine in the same local network.
2. hbmqtt and publish2.py running in Ubuntu 16.04 LTE virtual machine (the VM itself is running on Windows). Three web-subscribers running on the same machine but outside of the VM (i.e. natively on Windows).

Publishing rate can be adjusted by editing the sleep interval here:
https://github.com/veter-team/mechspeak/blob/master/src/publish2.py#L38

Running the test on RPi with approx. 30 FPS or in the VM with approx. 60FPS will result in hbmqtt server crash after about 10 seconds of operation. Please see attached file for my configuration file and logs generated by hbmqtt.

crash_info.txt