Source code for airflow.executors.local_executor

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"""
LocalExecutor

.. seealso::
    For more information on how the LocalExecutor works, take a look at the guide:
    :ref:`executor:LocalExecutor`
"""
import logging
import os
import subprocess
from abc import abstractmethod
from multiprocessing import Manager, Process
from multiprocessing.managers import SyncManager
from queue import Empty, Queue
from typing import Any, List, Optional, Tuple, Union

from setproctitle import setproctitle

from airflow import settings
from airflow.exceptions import AirflowException
from airflow.executors.base_executor import NOT_STARTED_MESSAGE, PARALLELISM, BaseExecutor, CommandType
from airflow.models.taskinstance import TaskInstanceKey, TaskInstanceStateType
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.state import State

# This is a work to be executed by a worker.
# It can Key and Command - but it can also be None, None which is actually a
# "Poison Pill" - worker seeing Poison Pill should take the pill and ... die instantly.
[docs]ExecutorWorkType = Tuple[Optional[TaskInstanceKey], Optional[CommandType]]
[docs]class LocalWorkerBase(Process, LoggingMixin): """ LocalWorkerBase implementation to run airflow commands. Executes the given command and puts the result into a result queue when done, terminating execution. :param result_queue: the queue to store result state """ def __init__(self, result_queue: 'Queue[TaskInstanceStateType]'): super().__init__(target=self.do_work) self.daemon: bool = True self.result_queue: 'Queue[TaskInstanceStateType]' = result_queue
[docs] def run(self): # We know we've just started a new process, so lets disconnect from the metadata db now settings.engine.pool.dispose() settings.engine.dispose() return super().run()
[docs] def execute_work(self, key: TaskInstanceKey, command: CommandType) -> None: """ Executes command received and stores result state in queue. :param key: the key to identify the task instance :param command: the command to execute """ if key is None: return self.log.info("%s running %s", self.__class__.__name__, command) if settings.EXECUTE_TASKS_NEW_PYTHON_INTERPRETER: state = self._execute_work_in_subprocess(command) else: state = self._execute_work_in_fork(command) self.result_queue.put((key, state))
[docs] def _execute_work_in_subprocess(self, command: CommandType) -> str: try: subprocess.check_call(command, close_fds=True) return State.SUCCESS except subprocess.CalledProcessError as e: self.log.error("Failed to execute task %s.", str(e)) return State.FAILED
[docs] def _execute_work_in_fork(self, command: CommandType) -> str: pid = os.fork() if pid: # In parent, wait for the child pid, ret = os.waitpid(pid, 0) return State.SUCCESS if ret == 0 else State.FAILED from airflow.sentry import Sentry ret = 1 try: import signal from airflow.cli.cli_parser import get_parser signal.signal(signal.SIGINT, signal.SIG_DFL) signal.signal(signal.SIGTERM, signal.SIG_DFL) signal.signal(signal.SIGUSR2, signal.SIG_DFL) parser = get_parser() # [1:] - remove "airflow" from the start of the command args = parser.parse_args(command[1:]) args.shut_down_logging = False setproctitle(f"airflow task supervisor: {command}") args.func(args) ret = 0 return State.SUCCESS except Exception as e: self.log.error("Failed to execute task %s.", str(e)) finally: Sentry.flush() logging.shutdown() os._exit(ret) raise RuntimeError('unreachable -- keep mypy happy')
@abstractmethod
[docs] def do_work(self): """Called in the subprocess and should then execute tasks""" raise NotImplementedError()
[docs]class LocalWorker(LocalWorkerBase): """ Local worker that executes the task. :param result_queue: queue where results of the tasks are put. :param key: key identifying task instance :param command: Command to execute """ def __init__( self, result_queue: 'Queue[TaskInstanceStateType]', key: TaskInstanceKey, command: CommandType ): super().__init__(result_queue) self.key: TaskInstanceKey = key self.command: CommandType = command
[docs] def do_work(self) -> None: self.execute_work(key=self.key, command=self.command)
[docs]class QueuedLocalWorker(LocalWorkerBase): """ LocalWorker implementation that is waiting for tasks from a queue and will continue executing commands as they become available in the queue. It will terminate execution once the poison token is found. :param task_queue: queue from which worker reads tasks :param result_queue: queue where worker puts results after finishing tasks """ def __init__(self, task_queue: 'Queue[ExecutorWorkType]', result_queue: 'Queue[TaskInstanceStateType]'): super().__init__(result_queue=result_queue) self.task_queue = task_queue
[docs] def do_work(self) -> None: while True: try: key, command = self.task_queue.get() except EOFError: self.log.info( "Failed to read tasks from the task queue because the other " "end has closed the connection. Terminating worker %s.", self.name, ) break try: if key is None or command is None: # Received poison pill, no more tasks to run break self.execute_work(key=key, command=command) finally: self.task_queue.task_done()
[docs]class LocalExecutor(BaseExecutor): """ LocalExecutor executes tasks locally in parallel. It uses the multiprocessing Python library and queues to parallelize the execution of tasks. :param parallelism: how many parallel processes are run in the executor """ def __init__(self, parallelism: int = PARALLELISM): super().__init__(parallelism=parallelism) self.manager: Optional[SyncManager] = None self.result_queue: Optional['Queue[TaskInstanceStateType]'] = None self.workers: List[QueuedLocalWorker] = [] self.workers_used: int = 0 self.workers_active: int = 0 self.impl: Optional[ Union['LocalExecutor.UnlimitedParallelism', 'LocalExecutor.LimitedParallelism'] ] = None
[docs] class UnlimitedParallelism: """ Implements LocalExecutor with unlimited parallelism, starting one process per each command to execute. :param executor: the executor instance to implement. """ def __init__(self, executor: 'LocalExecutor'): self.executor: 'LocalExecutor' = executor
[docs] def start(self) -> None: """Starts the executor.""" self.executor.workers_used = 0 self.executor.workers_active = 0
[docs] def execute_async( self, key: TaskInstanceKey, command: CommandType, queue: Optional[str] = None, executor_config: Optional[Any] = None, ) -> None: """ Executes task asynchronously. :param key: the key to identify the task instance :param command: the command to execute :param queue: Name of the queue :param executor_config: configuration for the executor """ if not self.executor.result_queue: raise AirflowException(NOT_STARTED_MESSAGE) local_worker = LocalWorker(self.executor.result_queue, key=key, command=command) self.executor.workers_used += 1 self.executor.workers_active += 1 local_worker.start()
[docs] def sync(self) -> None: """Sync will get called periodically by the heartbeat method.""" if not self.executor.result_queue: raise AirflowException("Executor should be started first") while not self.executor.result_queue.empty(): results = self.executor.result_queue.get() self.executor.change_state(*results) self.executor.workers_active -= 1
[docs] def end(self) -> None: """ This method is called when the caller is done submitting job and wants to wait synchronously for the job submitted previously to be all done. """ while self.executor.workers_active > 0: self.executor.sync()
[docs] class LimitedParallelism: """ Implements LocalExecutor with limited parallelism using a task queue to coordinate work distribution. :param executor: the executor instance to implement. """ def __init__(self, executor: 'LocalExecutor'): self.executor: 'LocalExecutor' = executor self.queue: Optional['Queue[ExecutorWorkType]'] = None
[docs] def start(self) -> None: """Starts limited parallelism implementation.""" if not self.executor.manager: raise AirflowException(NOT_STARTED_MESSAGE) self.queue = self.executor.manager.Queue() if not self.executor.result_queue: raise AirflowException(NOT_STARTED_MESSAGE) self.executor.workers = [ QueuedLocalWorker(self.queue, self.executor.result_queue) for _ in range(self.executor.parallelism) ] self.executor.workers_used = len(self.executor.workers) for worker in self.executor.workers: worker.start()
[docs] def execute_async( self, key: TaskInstanceKey, command: CommandType, queue: Optional[str] = None, executor_config: Optional[Any] = None, ) -> None: """ Executes task asynchronously. :param key: the key to identify the task instance :param command: the command to execute :param queue: name of the queue :param executor_config: configuration for the executor """ if not self.queue: raise AirflowException(NOT_STARTED_MESSAGE) self.queue.put((key, command))
[docs] def sync(self): """Sync will get called periodically by the heartbeat method.""" while True: try: results = self.executor.result_queue.get_nowait() try: self.executor.change_state(*results) finally: self.executor.result_queue.task_done() except Empty: break
[docs] def end(self): """Ends the executor. Sends the poison pill to all workers.""" for _ in self.executor.workers: self.queue.put((None, None)) # Wait for commands to finish self.queue.join() self.executor.sync()
[docs] def start(self) -> None: """Starts the executor""" self.manager = Manager() self.result_queue = self.manager.Queue() self.workers = [] self.workers_used = 0 self.workers_active = 0 self.impl = ( LocalExecutor.UnlimitedParallelism(self) if self.parallelism == 0 else LocalExecutor.LimitedParallelism(self) ) self.impl.start()
[docs] def execute_async( self, key: TaskInstanceKey, command: CommandType, queue: Optional[str] = None, executor_config: Optional[Any] = None, ) -> None: """Execute asynchronously.""" if not self.impl: raise AirflowException(NOT_STARTED_MESSAGE) self.validate_command(command) self.impl.execute_async(key=key, command=command, queue=queue, executor_config=executor_config)
[docs] def sync(self) -> None: """Sync will get called periodically by the heartbeat method.""" if not self.impl: raise AirflowException(NOT_STARTED_MESSAGE) self.impl.sync()
[docs] def end(self) -> None: """ Ends the executor. :return: """ if not self.impl: raise AirflowException(NOT_STARTED_MESSAGE) if not self.manager: raise AirflowException(NOT_STARTED_MESSAGE) self.log.info( "Shutting down LocalExecutor" "; waiting for running tasks to finish. Signal again if you don't want to wait." ) self.impl.end() self.manager.shutdown()
[docs] def terminate(self):
"""Terminate the executor is not doing anything."""

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