In this video we want to turn our Google Photos clone from single-threaded to multi-threaded, to generate thumbnails much faster than before.

But there are a couple of challenges along the way. We'll learn that using Java's Parallel File Streams seems to be a buggy endeavor, so we'll fall back on good, old ExecutorServices.

But how many threads should we use to generate thumbnails? How can threads get in conflict with each other? How do we make our program fail-safe for threading issues?

Watch to find out!