#55020 gantt view is not getting updatedin realtime

[yimingpeng]

Hello there,

This PR is an attempt to fix #55020 where the gantt chart wasn't showing real-time progress for running tasks.

closes: #55020

After applying the fix:

Screen.Recording.2025-09-01.at.9.18.13.PM.mov

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[guan404ming]

Thanks for fix, left some comments~

[yimingpeng]

Hello @guan404ming,

Thanks for all the great suggestions, I believe I have addressed them, also made a few more changes, e..g, expanding to other pending tasks (isStatePending) which was checking running only. Please help review again, thanks.

Here is the expanded test dag from the original issue post:

from datetime import datetime, timedelta

from airflow import DAG
from airflow.providers.standard.operators.bash import BashOperator
from airflow.providers.standard.operators.python import PythonOperator
from airflow.providers.standard.sensors.filesystem import FileSensor
from airflow.utils.task_group import TaskGroup

def task_that_fails():
    raise Exception("This task always fails for testing")

def task_that_succeeds():
    print("This task succeeds")
    return "success"

dag = DAG(
    'test_gantt_chart_dag',
    start_date=datetime(2025, 7, 1),
    schedule=None,
    is_paused_upon_creation=False,
    catchup=False,
    max_active_runs=1,
    default_args={
        'retries': 2,
        'retry_delay': timedelta(seconds=10),
    }
)

long_running_task = BashOperator(
    task_id="long_running_task",
    bash_command="echo 'Starting long task'; sleep 180; echo 'Long task completed'",
    dag=dag
)

queued_task = BashOperator(
    task_id="queued_task", 
    bash_command="echo 'Queued task executed'; sleep 30",
    dag=dag,
    pool='default_pool',
    pool_slots=10
)

failing_task = PythonOperator(
    task_id="failing_task",
    python_callable=task_that_fails,
    dag=dag
)

waiting_sensor = FileSensor(
    task_id="waiting_sensor",
    filepath="/tmp/nonexistent_file_for_testing.txt",
    timeout=300,
    poke_interval=30,
    dag=dag
)

scheduled_task = BashOperator(
    task_id="scheduled_task",
    bash_command="echo 'Scheduled task executed'; sleep 15",
    dag=dag
)

quick_success_task = PythonOperator(
    task_id="quick_success_task",
    python_callable=task_that_succeeds,
    dag=dag
)

upstream_failed_task = BashOperator(
    task_id="upstream_failed_task",
    bash_command="echo 'This should not run due to upstream failure'",
    dag=dag
)

with TaskGroup("processing_group", dag=dag) as processing_group:
    
    group_start = BashOperator(
        task_id="group_start",
        bash_command="echo 'Group starting'; sleep 5",
        dag=dag,
    )
    
    parallel_task_1 = BashOperator(
        task_id="parallel_task_1", 
        bash_command="echo 'Parallel task 1 running'; sleep 60",
        dag=dag,
    )
    
    parallel_task_2 = PythonOperator(
        task_id="parallel_task_2",
        python_callable=task_that_fails,
        dag=dag,
    )
    
    parallel_task_3 = BashOperator(
        task_id="parallel_task_3",
        bash_command="echo 'Parallel task 3 running'; sleep 45",
        dag=dag,
    )
    
    group_end = BashOperator(
        task_id="group_end",
        bash_command="echo 'Group completed'; sleep 10",
        trigger_rule="none_failed_min_one_success",
        dag=dag,
    )
    
    group_start >> [parallel_task_1, parallel_task_2, parallel_task_3] >> group_end

final_task = BashOperator(
    task_id="final_task",
    bash_command="echo 'All processing completed'",
    dag=dag
)

long_running_task >> scheduled_task
quick_success_task >> queued_task
failing_task >> upstream_failed_task
waiting_sensor >> scheduled_task
processing_group >> final_task

Here is the new recording after the fix is applied:

Screen.Recording.2025-09-02.at.11.13.34.PM.mov

[guan404ming]

Overall looks good, one nit

[guan404ming]

Overall looks good!

cc @bbovenzi @pierrejeambrun
would appreciate it if you could take another look when you have a moment, thanks!

[guan404ming]

@yimingpeng please help rebase and fix the tests, thanks!

[yimingpeng]

hello @bbovenzi, thanks for the code review, I guess you meant DEFAULT_DATETIME_FORMAT_WITH_TZ ? Can you have another review pls? if I misunderstood anything here, please correct me, thanks