Implemented __del__ to clean up hanging coroutines
#496
| Job | Run time |
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| 8m 51s | |
| 9m 51s | |
| 10m 5s | |
| 8m 58s | |
| 11m 3s | |
| 11m 7s | |
| 9m 15s | |
| 10m 57s | |
| 11m 8s | |
| 8m 4s | |
| 11m 2s | |
| 9m 58s | |
| 8m 24s | |
| 10m 48s | |
| 10m 42s | |
| 2h 30m 13s |