loss nan error when set filter_empty_gt=False about universenet

[shinya7y]

A possible solution is applying this fix open-mmlab/mmdetection#3702
to gfl_head.py.

if len(pos_inds) == 0: weight_targets become 0,
avg_factor may become 0, resulting in nan.

[whut2962575697]

Hello，do you fix the issue? #13

[shinya7y]

I updated the master branch with the abovementioned fix.
If the issue persists, please let me know more details.

[zhengye1995]

I updated the master branch with the abovementioned fix.
If the issue persists, please let me know more details.

Thanks for your replay, it works. But I still need to reduced the learning rate and tried to increase the warm-up step, which may results in the performance is not well.

[shinya7y]

I close this issue.
If there are performance issues (e.g., lower AP than the baselines ATSS and GFL), please open another issue.