c# - Spinlocks, How Useful Are They?

Question

How often do you find yourself actually using spinlocks in your code? How common is it to come across a situation where using a busy loop actually outperforms the usage of locks?
Personally, when I write some sort of code that requires thread safety, I tend to benchmark it with different synchronization primitives, and as far as it goes, it seems like using locks gives better performance than using spinlocks. No matter for how little time I actually hold the lock, the amount of contention I receive when using spinlocks is far greater than the amount I get from using locks (of course, I run my tests on a multiprocessor machine).

I realize that it's more likely to come across a spinlock in "low-level" code, but I'm interested to know whether you find it useful in even a more high-level kind of programming?

Answer 1

It depends on what you're doing. In general application code, you'll want to avoid spinlocks.

In low-level stuff where you'll only hold the lock for a couple of instructions, and latency is important, a spinlock mat be a better solution than a lock. But those cases are rare, especially in the kind of applications where C# is typically used.