CPU high due to locking
When multiple threads compete for the same lock, CPU gets spent on synchronization overhead instead of productive work.
Evidence to look for
perf shows mutex or spinlock functions in hot stacks
Adding more threads makes latency worse
CPU-per-transaction rises with concurrency
What it usually means
The system is spending CPU cycles waiting for locks instead of doing useful work. More concurrency makes it worse, not better.
What to do next
- 1Narrow critical sections
- 2Reduce shared-state access patterns
- 3Consider lock-free data structures for hot paths
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