TriggerEvent fires, and then defers a second time (doesn't fire a second time though). #18392

Apache Airflow version

2.2.0b1 (beta snapshot)

Operating System

debian buster

Versions of Apache Airflow Providers

n/a

Deployment

Astronomer

Deployment details

Helm info:

helm repo add astronomer https://helm.astronomer.io
cat <<- 'EOF'  | helm install airflow astronomer/airflow --namespace airflow -f -
airflowVersion: 2.2.0
defaultAirflowRepository: myrepo
defaultAirflowTag: myimagetag
executor: KubernetesExecutor
images:
  airflow:
    repository: myrepo
    pullPolicy: Always
  pod_template:
    repository: myrepo
    pullPolicy: Always
triggerer:
  serviceAccount:
    create: True
EOF

Dockerfile:

FROM quay.io/astronomer/ap-airflow-dev:2.2.0-buster-43897
COPY ./dags/ ./dags/

the dag

What happened

Six tasks deferred for a random (but deterministic) amount of time, and the triggerer fired six events. Two of those events then deferred a second time, which wasn't necessary because they had already fired. Looks like a race condition.

Here are the triggerer logs: https://gist.github.com/MatrixManAtYrService/8d1d0c978465aa249e8bd0498cc08031#file-triggerer-log-L29

Note that most deferrals only appear once, but the ones for "Aligator" and "Bear" appear twice.

What you expected to happen

Six tasks deferred, six tasks fires, no extra deferrals.

How to reproduce

Run the dag in this gist with the kubernetes executor (be sure there's a triggerer running). Notice that some of the triggerer log messages appear nore than once. Those represent superfluous computation.

Anything else

No response

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct