Spinlock vs Mutex: When to Spin and When to Sleep for Best Performance

Описание: Ever had a 16‑core server pegged at 100% while doing nothing useful? This video shows why the wrong synchronization primitive can turn your system into a performance nightmare, and how to avoid that trap every time. You will learn the real, practical differences between a spin lock and a mutex, the hidden dangers people miss, and a simple rulebook for choosing the right tool. Key takeaways:

Spin locks are the impatient spinner, burning CPU in a tight user‑space loop. They win when critical sections are extremely short, generally under ~100 nanoseconds. If a protected operation takes milliseconds, a spin lock will incinerate CPU time. Example: a 10 millisecond critical section with a spin lock is a disaster.
Mutexes are the patient sleeper, using OS sleep/wake (futex) and costing a context switch, typically microseconds. They free the CPU for other work, so use them for longer critical sections or higher contention.
Critical gotchas include preemption, priority inversion, and cache line bouncing. A thread holding a spin lock can get preempted and block progress, a high priority thread can starve the lock holder, and many spinners cause heavy cache coherency traffic.
Practical decision matrix: measure your critical section latency and contention level, then choose. No silver bullets, only measurement.

Actionable diagnostics shown in the video:

Watch CPU usage with top to see spinning threads pegging cores.
Count futex system calls with strace to make kernel overhead tangible.
Use perf (perf stat) to measure context switches and cache misses, and inspect /proc to see thread states.

Watch the full video to see live demos and proofs that make the difference painfully obvious, and try the same checks on your app. Tell me in the comments which lock you switched and what your profiling showed, or share a command that helped you debug this. If this helped, please like and subscribe for more performance deep dives. This video has been generated by