use_file: replace mutex with nanosleep-based loop
#20
| Job | Run time |
|---|---|
| 18s | |
| 2m 10s | |
| 14s | |
| 2m 42s |
nanosleep-based loop
#20
| Job | Run time |
|---|---|
| 18s | |
| 2m 10s | |
| 14s | |
| 2m 42s |