It's definitely doing synchronization behind the scenes, no argument here. BlockingQueues in Java seem to use ReentrantLocks everywhere. It's outsourcing the lock to people who understand locks better.
It just abstracts this detail away for me, and I personally trust the libraries implementing these abstractions to be more correct than some ad hoc thing I write. It's an abstraction that I personally find a lot easier to reason about, and so my thinking is this: if my reasoning is more likely to be correct because of the easier abstraction, and the internal synchronization is more likely to be correct, then it's more likely that my code will be correct.
I don't do super low-level stuff at all, most of my stuff ends up touching a network, so the small differences between the built-in synchronized structures vs the regular ones really don't matter since any small gains I'd get on that will be eaten the first time I hit the network, so a considerably higher ROI for me is almost always figuring out how to reduce latency.
If I did C or C++, I'd probably have different opinions on this stuff.
It just abstracts this detail away for me, and I personally trust the libraries implementing these abstractions to be more correct than some ad hoc thing I write. It's an abstraction that I personally find a lot easier to reason about, and so my thinking is this: if my reasoning is more likely to be correct because of the easier abstraction, and the internal synchronization is more likely to be correct, then it's more likely that my code will be correct.
I don't do super low-level stuff at all, most of my stuff ends up touching a network, so the small differences between the built-in synchronized structures vs the regular ones really don't matter since any small gains I'd get on that will be eaten the first time I hit the network, so a considerably higher ROI for me is almost always figuring out how to reduce latency.
If I did C or C++, I'd probably have different opinions on this stuff.