Fix race conditions on loop._ready_len
#722
| Job | Run time |
|---|---|
| 15m 53s | |
| 8m 54s | |
| 9m 2s | |
| 8m 8s | |
| 16m 43s | |
| 9m 25s | |
| 9m 35s | |
| 17m 48s | |
| 7m 11s | |
| 13m 48s | |
| 16m 11s | |
| 16m 4s | |
| 8m 22s | |
| 8m 41s | |
| 9m 51s | |
| 16m 48s | |
| 0s | |
| 9m 2s | |
| 8m 41s | |
| 8m 8s | |
| 16m 4s | |
| 9m 35s | |
| 16m 11s | |
| 16m 43s | |
| 8m 54s | |
| 9m 25s | |
| 16m 48s | |
| 5m 57s | |
| 17m 48s | |
| 9m 51s | |
| 15m 53s | |
| 8m 22s | |
| 13m 48s | |
| -1s | |
| 8m 41s | |
| 15m 53s | |
| 8m 8s | |
| 16m 43s | |
| 16m 4s | |
| 13m 48s | |
| 5m 51s | |
| 16m 48s | |
| 9m 51s | |
| 16m 11s | |
| 9m 35s | |
| 8m 54s | |
| 8m 22s | |
| 9m 25s | |
| 17m 48s | |
| 9m 2s | |
| -1s | |
| 9h 34m 36s |