| #!/usr/bin/env python |
| # Copyright 2014 the V8 project authors. All rights reserved. |
| # Use of this source code is governed by a BSD-style license that can be |
| # found in the LICENSE file. |
| |
| # for py2/py3 compatibility |
| from __future__ import print_function |
| |
| from contextlib import contextmanager |
| from multiprocessing import Process, Queue |
| import os |
| import signal |
| import time |
| import traceback |
| |
| try: |
| from queue import Empty # Python 3 |
| except ImportError: |
| from Queue import Empty # Python 2 |
| |
| from . import command |
| |
| |
| def setup_testing(): |
| """For testing only: Use threading under the hood instead of multiprocessing |
| to make coverage work. |
| """ |
| global Queue |
| global Process |
| del Queue |
| del Process |
| try: |
| from queue import Queue # Python 3 |
| except ImportError: |
| from Queue import Queue # Python 2 |
| |
| from threading import Thread as Process |
| # Monkeypatch threading Queue to look like multiprocessing Queue. |
| Queue.cancel_join_thread = lambda self: None |
| # Monkeypatch os.kill and add fake pid property on Thread. |
| os.kill = lambda *args: None |
| Process.pid = property(lambda self: None) |
| |
| |
| class NormalResult(): |
| def __init__(self, result): |
| self.result = result |
| self.exception = None |
| |
| class ExceptionResult(): |
| def __init__(self, exception): |
| self.exception = exception |
| |
| |
| class MaybeResult(): |
| def __init__(self, heartbeat, value): |
| self.heartbeat = heartbeat |
| self.value = value |
| |
| @staticmethod |
| def create_heartbeat(): |
| return MaybeResult(True, None) |
| |
| @staticmethod |
| def create_result(value): |
| return MaybeResult(False, value) |
| |
| |
| def Worker(fn, work_queue, done_queue, |
| process_context_fn=None, process_context_args=None): |
| """Worker to be run in a child process. |
| The worker stops when the poison pill "STOP" is reached. |
| """ |
| try: |
| kwargs = {} |
| if process_context_fn and process_context_args is not None: |
| kwargs.update(process_context=process_context_fn(*process_context_args)) |
| for args in iter(work_queue.get, "STOP"): |
| try: |
| done_queue.put(NormalResult(fn(*args, **kwargs))) |
| except command.AbortException: |
| # SIGINT, SIGTERM or internal hard timeout. |
| break |
| except Exception as e: |
| traceback.print_exc() |
| print(">>> EXCEPTION: %s" % e) |
| done_queue.put(ExceptionResult(e)) |
| # When we reach here on normal tear down, all items have been pulled from |
| # the done_queue before and this should have no effect. On fast abort, it's |
| # possible that a fast worker left items on the done_queue in memory, which |
| # will never be pulled. This call purges those to avoid a deadlock. |
| done_queue.cancel_join_thread() |
| except KeyboardInterrupt: |
| assert False, 'Unreachable' |
| |
| |
| @contextmanager |
| def without_sig(): |
| int_handler = signal.signal(signal.SIGINT, signal.SIG_IGN) |
| term_handler = signal.signal(signal.SIGTERM, signal.SIG_IGN) |
| try: |
| yield |
| finally: |
| signal.signal(signal.SIGINT, int_handler) |
| signal.signal(signal.SIGTERM, term_handler) |
| |
| |
| class Pool(): |
| """Distributes tasks to a number of worker processes. |
| New tasks can be added dynamically even after the workers have been started. |
| Requirement: Tasks can only be added from the parent process, e.g. while |
| consuming the results generator.""" |
| |
| # Factor to calculate the maximum number of items in the work/done queue. |
| # Necessary to not overflow the queue's pipe if a keyboard interrupt happens. |
| BUFFER_FACTOR = 4 |
| |
| def __init__(self, num_workers, heartbeat_timeout=1): |
| self.num_workers = num_workers |
| self.processes = [] |
| self.terminated = False |
| self.abort_now = False |
| |
| # Invariant: processing_count >= #work_queue + #done_queue. It is greater |
| # when a worker takes an item from the work_queue and before the result is |
| # submitted to the done_queue. It is equal when no worker is working, |
| # e.g. when all workers have finished, and when no results are processed. |
| # Count is only accessed by the parent process. Only the parent process is |
| # allowed to remove items from the done_queue and to add items to the |
| # work_queue. |
| self.processing_count = 0 |
| self.heartbeat_timeout = heartbeat_timeout |
| |
| # Disable sigint and sigterm to prevent subprocesses from capturing the |
| # signals. |
| with without_sig(): |
| self.work_queue = Queue() |
| self.done_queue = Queue() |
| |
| def imap_unordered(self, fn, gen, |
| process_context_fn=None, process_context_args=None): |
| """Maps function "fn" to items in generator "gen" on the worker processes |
| in an arbitrary order. The items are expected to be lists of arguments to |
| the function. Returns a results iterator. A result value of type |
| MaybeResult either indicates a heartbeat of the runner, i.e. indicating |
| that the runner is still waiting for the result to be computed, or it wraps |
| the real result. |
| |
| Args: |
| process_context_fn: Function executed once by each worker. Expected to |
| return a process-context object. If present, this object is passed |
| as additional argument to each call to fn. |
| process_context_args: List of arguments for the invocation of |
| process_context_fn. All arguments will be pickled and sent beyond the |
| process boundary. |
| """ |
| if self.terminated: |
| return |
| try: |
| internal_error = False |
| gen = iter(gen) |
| self.advance = self._advance_more |
| |
| # Disable sigint and sigterm to prevent subprocesses from capturing the |
| # signals. |
| with without_sig(): |
| for w in range(self.num_workers): |
| p = Process(target=Worker, args=(fn, |
| self.work_queue, |
| self.done_queue, |
| process_context_fn, |
| process_context_args)) |
| p.start() |
| self.processes.append(p) |
| |
| self.advance(gen) |
| while self.processing_count > 0: |
| while True: |
| try: |
| # Read from result queue in a responsive fashion. If available, |
| # this will return a normal result immediately or a heartbeat on |
| # heartbeat timeout (default 1 second). |
| result = self._get_result_from_queue() |
| except: |
| # TODO(machenbach): Handle a few known types of internal errors |
| # gracefully, e.g. missing test files. |
| internal_error = True |
| continue |
| |
| if self.abort_now: |
| # SIGINT, SIGTERM or internal hard timeout. |
| return |
| |
| yield result |
| break |
| |
| self.advance(gen) |
| except KeyboardInterrupt: |
| assert False, 'Unreachable' |
| except Exception as e: |
| traceback.print_exc() |
| print(">>> EXCEPTION: %s" % e) |
| finally: |
| self._terminate() |
| |
| if internal_error: |
| raise Exception("Internal error in a worker process.") |
| |
| def _advance_more(self, gen): |
| while self.processing_count < self.num_workers * self.BUFFER_FACTOR: |
| try: |
| self.work_queue.put(next(gen)) |
| self.processing_count += 1 |
| except StopIteration: |
| self.advance = self._advance_empty |
| break |
| |
| def _advance_empty(self, gen): |
| pass |
| |
| def add(self, args): |
| """Adds an item to the work queue. Can be called dynamically while |
| processing the results from imap_unordered.""" |
| assert not self.terminated |
| |
| self.work_queue.put(args) |
| self.processing_count += 1 |
| |
| def abort(self): |
| """Schedules abort on next queue read. |
| |
| This is safe to call when handling SIGINT, SIGTERM or when an internal |
| hard timeout is reached. |
| """ |
| self.abort_now = True |
| |
| def _terminate(self): |
| """Terminates execution and cleans up the queues. |
| |
| If abort() was called before termination, this also terminates the |
| subprocesses and doesn't wait for ongoing tests. |
| """ |
| if self.terminated: |
| return |
| self.terminated = True |
| |
| # Drain out work queue from tests |
| try: |
| while True: |
| self.work_queue.get(True, 0.1) |
| except Empty: |
| pass |
| |
| # Make sure all processes stop |
| for _ in self.processes: |
| # During normal tear down the workers block on get(). Feed a poison pill |
| # per worker to make them stop. |
| self.work_queue.put("STOP") |
| |
| if self.abort_now: |
| for p in self.processes: |
| os.kill(p.pid, signal.SIGTERM) |
| |
| for p in self.processes: |
| p.join() |
| |
| # Drain the queues to prevent stderr chatter when queues are garbage |
| # collected. |
| try: |
| while True: self.work_queue.get(False) |
| except: |
| pass |
| try: |
| while True: self.done_queue.get(False) |
| except: |
| pass |
| |
| def _get_result_from_queue(self): |
| """Attempts to get the next result from the queue. |
| |
| Returns: A wrapped result if one was available within heartbeat timeout, |
| a heartbeat result otherwise. |
| Raises: |
| Exception: If an exception occured when processing the task on the |
| worker side, it is reraised here. |
| """ |
| while True: |
| try: |
| result = self.done_queue.get(timeout=self.heartbeat_timeout) |
| self.processing_count -= 1 |
| if result.exception: |
| raise result.exception |
| return MaybeResult.create_result(result.result) |
| except Empty: |
| return MaybeResult.create_heartbeat() |
