97 Things Every Java Programmer Should Know

Chapter 82. Threads Are Infrastructure; Treat Them as Such

Russel Winder

How many Java programmers manage—or even think about—stack use during their programming? More or less none. The vast majority of Java programmers leave stack management to the compiler and runtime system.

How many Java programmers manage—or even think about—heap use during their programming? Very few. The majority of Java programmers assume the garbage collection system will deal with all heap management.

So why are so many Java programmers managing all their threads manually? Because that is what they were taught to do. From the beginning, Java supported shared memory multithreading, which was almost certainly a big error.

Almost all that most Java programmers know about concurrency and parallelism is founded on the theory of constructing operating systems from the 1960s. If you are writing an operating system then this is all good stuff, but are most Java programs actually operating systems? No. So a rethink is in order.

If your code has any synchronized statements, locks, mutexes—all the paraphernalia of operating systems—then in all likelihood, you are doing it wrong. This is the wrong level of abstraction for most Java programmers. Just as stack space and heap space are managed resources, threads should be considered managed resources. Instead of creating threads explicitly and managing them, construct ...