The ArrayAdapter keeps items in the memory. Meaning that it will lose them all when the PHP process terminates. So as long as you don’t have a long running process where you query the same item more than once the behaviour you describe looks expected to me.

@xabbuh Hi, sorry to doubt your message, but from my point of view the idea of ArrayAdapter is to keep data in runtime memory not to query them throughout even the single http request, isn't it? What is the point of storing some data in "global" memory for one-time query at all? I can put it in the local variable instead.
More to say, we are now heading to long-living application (using Roadrunner), where some data is worth storing in runtime between requests rather than quering it from Redis for every request. And for long-living case this situation is even more sensitive for us.

I missed that you query for the same item inside the loop. Can you create a small example application that allows to reproduce your issue?

$cache->save($item);

This line goes to all adapters so that all of them have it. That's the explanation why redis is always hit.

This line goes to all adapters so that all of them have it.

Well, this is pretty understandable, but I still don't think it is okay to call Redis fetch 10 times.

You need to move that line inside the "if". If you don't want that redis to be called 10 times, just don't write the code that asks for it :)
Closing as there is no bug here.