How does the new barrack system work after October 2016's update?
I'm not really clear on how the new training system works. I'm not asking about the quick train, I'm asking about the queues for normal training.
Do each 4 barracks simultaneously train a troop ? For example if you queue 4 archers, after 15 seconds 4 will come out? It doesn't seem to be. I also noticed that if I fill up a queue with dragons or such, the dark barrack queue is filled up too. Are they now connected ?
Let's take your example where you want to create 4 archers (assuming you have unlocked the archer unit in all of your 4 barracks, of course).
The barracks used to work like this :
Every barrack will create 1 archer in 25 seconds.
Now, it works like that :
The barracks put their efforts together and create one unit all at once. Thus, an archer will be created every 25 / 4 = 6.25 seconds. 4 archers will be trained in 4 x 6.25 = 25 seconds.
Basically, if you want to create a unit, it will now take the standard training time divided by the number of barracks that have unlocked the unit. However, this doesn't change the total training time of your army. Supercell made this change so it is easier to form high-capacity troops (such as golems (30) or P.E.K.K.As (25)), and so people don't have to wait ages to make such a donation. This is especially handy during clan war times.
"I also noticed that if I fill up a queue with dragons or such, the dark barrack queue is filled up too. Are they now connected ?"
Yes. This is one of the drawbacks of the update. Now, regular troops and dark troops cannot be created at the same time ; if you are currently training a dragon and you want a golem, you'll have to wait until your dragon is trained until you can start to train your golem.
Note : Imagine you have only one dark barrack upgraded to golems (capacity of the barrack : 70). The new system doesn't allow the barracks' capacity to stack. You still cannot create more than 2 golems in that case.
Useful link : Official Clash of Clans blog post.
After Oct 2016 update, Armies will be trained in sequence order which means only one troop will be trained at any point of time. The reason why they reduced the training time based on the barracks is due to follow reason:
Consider u have one barrack updated to Dragon and rest all updated to Healer
In this case u can only train one Dragon in the old training method.Hence, high training similar to old system.
Now assume that u have all barracks updated to Dragon. In old system you can train 4 Dragons in parallel.So, in 15Min u can train maximum 4 Dragons. If SuperCell didn't reduce the training time, in this case You will need to wait for ages.
But, they have reduced the training to make a balance. If you update all barracks to Dragon in current system, Dragon will take 3 Minutes.Hence, you can train 5 Dragons in same 15 Minutes even though u can train only Dragon at a time.
Good thing is u can donate any troop during Wars and also it took less time than old system.bad thing is If u include much Dark elixir Troops, it may take longer time than previous system.