YOLOv8-16bit/docs/reference/yolo/utils/callbacks/hub.md

---
description: Improve YOLOv5 model training with Ultralytics' on-train callbacks. Boost performance on-pretrain-routine-end, model-save, train/predict start.
keywords: Ultralytics, YOLO, callbacks, on_pretrain_routine_end, on_fit_epoch_end, on_train_start, on_val_start, on_predict_start, on_export_start
---

# on_pretrain_routine_end
---
:::ultralytics.yolo.utils.callbacks.hub.on_pretrain_routine_end
<br><br>

# on_fit_epoch_end
---
:::ultralytics.yolo.utils.callbacks.hub.on_fit_epoch_end
<br><br>

# on_model_save
---
:::ultralytics.yolo.utils.callbacks.hub.on_model_save
<br><br>

# on_train_end
---
:::ultralytics.yolo.utils.callbacks.hub.on_train_end
<br><br>

# on_train_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_train_start
<br><br>

# on_val_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_val_start
<br><br>

# on_predict_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_predict_start
<br><br>

# on_export_start
---
:::ultralytics.yolo.utils.callbacks.hub.on_export_start
<br><br>