Multiple Frontend/Backend Servers issue

[NeubauerJohannes]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	no
RFC?	no
Branch?	master

We are running PimCore in a multi docker-container setup with multiple frontend-nodes and backend-nodes (for administration).
Maintenance Jobs are run by one of the backend-nodes.

In this kind of setup the locking/release does not work (preventing multiple processes to run).
It would be nice to include besides the pid the server id (e.g. hostname) and not start a process if another server reports the process as running.

Expected behaviour:

• Do not start a process if another server reports it as running
• Remove dead pids only when on the running server via maintenance task (to be run on any server of course)

[dpfaffenbauer]

we would need to properly refactor the bundle and use the messenger to distribute the jobs. We currently don't have any resources allocated in further developing this bundle. we are still happy with reviewing and merging pull requests,