Airflow 并行运行任务

Question

我很困惑并行运行两个任务的工作气流如何。

这是我的达格：

import datetime as dt
from airflow import DAG
import os
from airflow.operators.bash_operator import BashOperator
from airflow.operators.python_operator import PythonOperator, BranchPythonOperator
from airflow.contrib.sensors.file_sensor import FileSensor
from airflow.operators.dagrun_operator import TriggerDagRunOperator

scriptAirflow = '/home/alexw/scriptAirflow/'
uploadPath='/apps/man-data/data/to_load/'
receiptPath= '/apps/man-data/data/to_receipt/'

def result():
    if(os.listdir(receiptPath)):
        for files in os.listdir(receiptPath):
            if files.startswith('MEM') and files.endswith('.csv'):
                return 'mem_script'
                pass
                print('Launching script for: '+files)
            elif files.startswith('FMS') and files.endswith('.csv'):
                return 'fms_script'
                pass
            else:
                pass   
    else:
        print('No script to launch')
        return "no_script"
        pass

def onlyCsvFiles():
    if(os.listdir(uploadPath)):
        for files in os.listdir(uploadPath):
            if files.startswith('MEM') or files.startswith('FMS') and files.endswith('.csv'):
                return 'move_good_file'
            else:
                return 'move_bad_file'
    else:
        pass

default_args = {
    'owner': 'testingA',
    'start_date': dt.datetime(2020, 2, 17),
    'retries': 1,
}

dag = DAG('tryingAirflow', default_args=default_args, description='airflow20',
          schedule_interval=None, catchup=False)

file_sensor = FileSensor(
    task_id="file_sensor",
    filepath=uploadPath,
    fs_conn_id='airflow_db',
    poke_interval=10,
    dag=dag,
)

onlyCsvFiles=BranchPythonOperator(
    task_id='only_csv_files',
    python_callable=onlyCsvFiles,
    trigger_rule='none_failed',
    dag=dag,)

move_good_file = BashOperator(
    task_id="move_good_file",
    bash_command='python3 '+scriptAirflow+'movingGoodFiles.py "{{ execution_date }}"',
    dag=dag,
)
move_bad_file = BashOperator(
    task_id="move_bad_file",
    bash_command='python3 '+scriptAirflow+'movingBadFiles.py "{{ execution_date }}"',
    dag=dag,
)
result_mv = BranchPythonOperator(
    task_id='result_mv',
    python_callable=result,
    trigger_rule='none_failed',
    dag=dag,
)
run_Mem_Script = BashOperator(
    task_id="mem_script",
    bash_command='python3 '+scriptAirflow+'memShScript.py "{{ execution_date }}"',
    dag=dag,
)
run_Fms_Script = BashOperator(
    task_id="fms_script",
    bash_command='python3 '+scriptAirflow+'fmsScript.py "{{ execution_date }}"',
    dag=dag,
)
skip_script= BashOperator(
    task_id="no_script",
    bash_command="echo No script to launch",
    dag=dag,
)

rerun_dag=TriggerDagRunOperator(
    task_id='rerun_dag',
    trigger_dag_id='tryingAirflow',
    trigger_rule='none_failed',
    dag=dag,
)

onlyCsvFiles.set_upstream(file_sensor)
onlyCsvFiles.set_upstream(file_sensor)
move_good_file.set_upstream(onlyCsvFiles)
move_bad_file.set_upstream(onlyCsvFiles)
result_mv.set_upstream(move_good_file)
result_mv.set_upstream(move_bad_file)
run_Fms_Script.set_upstream(result_mv)
run_Mem_Script.set_upstream(result_mv)
skip_script.set_upstream(result_mv)
rerun_dag.set_upstream(run_Fms_Script)
rerun_dag.set_upstream(run_Mem_Script)
rerun_dag.set_upstream(skip_script)

当需要选择结果中的任务时，如果我必须调用这两个任务，它只执行一个任务并跳过另一个任务。

我想在必要时同时执行这两项任务。对于我的airflow.cfg。问题是：如何使用 BranchPythonOperator 并行运行任务（如果不需要，则不并行运行）。

谢谢帮助！

Answer 1

如果您确实想运行两个脚本或不运行两个脚本，我会在需要并行运行的两个任务之前添加一个虚拟任务。当您使用 .Airflow 时，Airflow 将始终选择一个BranchPythonOperator分支来执行。

我会做出这些改变：

# import the DummyOperator
from airflow.operators.dummy_operator import DummyOperator

# modify the returns of the function result()
def result():
    if(os.listdir(receiptPath)):
        for files in os.listdir(receiptPath):
            if (files.startswith('MEM') and files.endswith('.csv') or 
                files.startswith('FMS') and files.endswith('.csv')):
                return 'run_scripts'
    else:
        print('No script to launch')
        return "no_script"

# add the dummy task
run_scripts = DummyOperator(
    task_id="run_scripts",
    dag=dag
)

# add dependency
run_scripts.set_upstream(result_mv)

# CHANGE two of the dependencies to
run_Fms_Script.set_upstream(run_scripts)
run_Mem_Script.set_upstream(run_scripts)

我必须承认我从未处理过LocalExecutor并行任务，但这应该确保您运行这两个任务，以防您想运行脚本。

编辑：

如果您想运行none、两者之一或两者，我认为最简单的方法是创建另一个任务，在 bash 中并行运行这两个脚本（或者至少它与 一起运行它们&）。我会做这样的事情：

# import the DummyOperator
from airflow.operators.dummy_operator import DummyOperator

# modify the returns of the function result() so that it chooses between 4 different outcomes
def result():
    if(os.listdir(receiptPath)):
        mem_flag = False
        fms_flag = False
        for files in os.listdir(receiptPath):
            if (files.startswith('MEM') and files.endswith('.csv')):
                mem_flag = True
            if (files.startswith('FMS') and files.endswith('.csv')):
                fms_flag = True
        if mem_flag and fms_flag:
            return "both_scripts"
        elif mem_flag:
            return "mem_script"
        elif fms_flag:
            return "fms_script"
        else:
            return "no_script"
    else:
        print('No script to launch')
        return "no_script"

# add the 'run both scripts' task
run_both_scripts = BashOperator(
    task_id="both_script",
    bash_command='python3 '+scriptAirflow+'memShScript.py "{{ execution_date }}" & python3 '+scriptAirflow+'fmsScript.py "{{ execution_date }}" &',
    dag=dag,
)

# add dependency
run_both_scripts.set_upstream(result_mv)