Spinlock
A spinlock is a low-level synchronization primitive used in concurrent programming to protect shared resources by causing a thread to repeatedly check (spin) until the lock becomes available, rather than blocking and yielding the CPU. It is implemented as a busy-wait loop where a thread continuously polls a lock variable, making it efficient for very short critical sections but wasteful for longer waits. Spinlocks are commonly used in operating system kernels, real-time systems, and high-performance computing where context switching overhead must be minimized.
Developers should learn and use spinlocks when implementing low-level synchronization in scenarios where lock hold times are extremely short (e.g., nanoseconds) and the overhead of putting a thread to sleep and waking it (context switching) would be more costly than spinning. They are essential in kernel development, real-time applications, and multi-threaded systems where performance is critical and predictable latency is required. However, they should be avoided in user-space applications with longer critical sections to prevent CPU waste and priority inversion issues.