Werk #4901: Reworked Livestatus Proxy to be more scalable

The livestatus proxy daemon has been reworked to use a multi process architecture. It now has a master process that mainly cares about monitoring the site processes. Each connected site has an own subprocess that manages all channels to this site and the clients that use these channels to communicate with the sites.

When you have a look at ps/top you should see something like this:

OMD[heute]:~$ ps -ef | grep liveproxyd
UID        PID  PPID  C STIME TTY          TIME CMD
heute     9261     1  0 11:40 ?        00:00:00 liveproxyd[master]
heute     9262  9261  0 11:40 ?        00:00:00 liveproxyd[heute_slave_1]
heute     9263  9261  0 11:40 ?        00:00:00 liveproxyd[heute_slave_2]

As you can may see there is the master process that has the process 1 as parent process. The site processes have the master as parent.

When one site process terminates for some reason the master will restart it. When the master is terminated all site processes will terminate too. In case of a restart or config reload the master will restart itself and stop all site processes and restart them again.

With this change the load of the livestatus proxy will now spread over multiple CPUs.

Side note: There is a new global setting Logging of the Livestatus Proxy that can be used to control the detail level of the log entries written to the var/log/liveproxyd.log log file. In case you experience any issues with the livestatus proxy daemon take a look at this log file and maybe increase the log level to get more details.

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