Celery with Redis and Django giving WorkerLostError on long running tasks - django

Question

I have a long running Celery task that computes the PDP of a feature. Below is the shared task that's run:
#shared_task
def get_pdp_single(bst, train_df, feature, value, f_id=-1):
x_temp = train_df.copy()
x_temp.iloc[:, f_id] = value
data = xgb.DMatrix(x_temp, feature_names=x_temp.columns.tolist())
predictions = (bst.predict(data))
avg_predictions = np.mean(predictions)
result_dict = {
"feature": feature,
"avg_predictions": avg_predictions.item()
}
return result_dict
I'm computing Hstatistics of all the features taken in the XGBoost model built. So, we have lots of such tasks being queued in the Broker (Redis). ~12k tasks gets queued into Redis for this.
I have a 8core 16GB VM on which I instantiate a single Celery worker to do this task. Each single child task takes ~40 seconds to complete, this is because XGBoost predict method takes its time to complete.
On such long running task, I'm invariably getting WorkerLostErrors and it is quite unpredictable when and how this is occurring. However, I'm pretty sure this is because of the number of tasks being queued on the broker, because ~4-5k tasks run fine on the same setup without any issues.
Below is the stack trace that I get on Celery.
Restarting celery worker (/~/anaconda3/envs/py35_clone_canary/bin/celery -A ba_tpe_python_service worker -Q staging_celery_queue --loglevel=info)
Traceback (most recent call last):
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/worker/worker.py", line 205, in start
self.blueprint.start(self)
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/bootsteps.py", line 119, in start
step.start(parent)
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/bootsteps.py", line 369, in start
return self.obj.start()
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/worker/consumer/consumer.py", line 318, in start
blueprint.start(self)
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/bootsteps.py", line 119, in start
step.start(parent)
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/worker/consumer/consumer.py", line 596, in start
c.loop(*c.loop_args())
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/worker/loops.py", line 74, in asynloop
state.maybe_shutdown()
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/celery-4.4.0rc3-py3.5.egg/celery/worker/state.py", line 80, in maybe_shutdown
raise WorkerShutdown(should_stop)
celery.exceptions.WorkerShutdown: 0
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/~/anaconda3/envs/py35_clone_canary/lib/python3.5/site-packages/billiard-3.6.1.0-py3.5.egg/billiard/pool.py", line 1267, in mark_as_worker_lost
human_status(exitcode)),
billiard.exceptions.WorkerLostError: Worker exited prematurely: exitcode 70.
I have also looked at multiple issues reported on the Github pages of Celery and Billiard. The solution have been mentioned as to take the latest version of Celery and Billiard. I have taken the latest master branch from their respective Git and built it in my environment but still facing the same issue
Celery version used: 4.4.0rc3
Billiard version used: 3.6.1.0
Please help me in debugging the issue.