# error: CPU at 100%: select with default spins in tight loop

- **ID:** `go/select-default-busy-loop`
- **Domain:** go
- **Category:** resource_error
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

A 'for { select { case ...: default: } }' loop with a default branch never blocks, so it consumes a full CPU core spinning when no case is ready.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| 1.18 | active | — | — |
| 1.22 | active | — | — |

## Workarounds

1. **** (95% success)
   ```
   Remove the default branch so select blocks until a case is ready
   ```
2. **** (85% success)
   ```
   If polling is required, add a time.After backoff: 'case <-time.After(100*time.Millisecond):'
   ```

## Dead Ends

- **** — Yields but still spins at high CPU; just slightly less hot (80% fail)
- **** — Starves other goroutines and hides rather than fixes the spin (85% fail)