Normalize thread naming of threads in add-ons

[Hilbrand]

A number of add-ons start there own threads. To track threads better I propose these threads should all name their thread using a specific name convention. My proposal is to use:

• If there is 1 thread::OH-binding-<thingUID>,
• If there are multiple threads: OH-binding-<thingUID>-<custom>. Where custom is a developer defined word that suggest which specific thread it is.

Some bindings use Executors. My suggested would be to either standardize to all use the org.eclipse.smarthome.core.common. ThreadPoolManager or another option to allow a generic Executors, but initialize with the openHAB NamedThreadFactory. The named thread factory/pool manager should than be initialized with binding-<thingUID>. Note that using the ThreadPoolManager` will add an incremental number to the thread name for each thread started.

[fwolter]

Many bindings append hostname and port number to the thread name. I think this is more meaningful than a number. I suggest to leave the part after the binding ID up to the binding developer.

[Hilbrand]

Yes that might be a better idea, to leave it to the developer. Maybe the ThingID and some additional info so one can see which thing has started the thread. Or just instead of bindingId use the thing UID. I'll update the text.

[kaikreuzer]

I'd like to mention that the general advice is to NOT use any threads at all within bindings. Most things should be possible to solve with the existing scheduler that is provided within the handlers. Requiring a dedicated thread should thus be an exception for the situations where it is really needed, such as continuously listening on TCP ports for events.

Please keep that in mind for all binding reviews!

[Hilbrand]

@kaikreuzer my idea is to go through all bindings and see how threads are used and see if we can make them consistent. For example some use thread.start, while others use a single thread executor. Some use our thread executor to create a thread pool, others use the generic executor. I don't know what is preferred. But would like if we can make a general guideline. (Besides don't use a thead when not needed) Do you have an opinion about this?

[kaikreuzer]

@Hilbrand Yes, I think a general guidelines makes sense.
Just like we offer thread pools through ThreadPoolManager, we should have a way to deal with single/permanent threads.
I don't have a strong opinion, how this guideline should look like, so feel free to suggest one. Aligning thread naming across all binings as a first step definitely makes sense as well 👍 .