v8/tools/testrunner/local/pool.py
machenbach@chromium.org 04043b3352 Fix keyboard interrupt in test driver.
Drain the queues to prevent failures when queues are garbage collected. Fails when interrupting test262 otherwise.

R=jkummerow@chromium.org

Review URL: https://codereview.chromium.org/286973004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@21334 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2014-05-15 15:01:27 +00:00

147 lines
4.4 KiB
Python

#!/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.
from multiprocessing import Event, Process, Queue
class NormalResult():
def __init__(self, result):
self.result = result
self.exception = False
self.break_now = False
class ExceptionResult():
def __init__(self):
self.exception = True
self.break_now = False
class BreakResult():
def __init__(self):
self.exception = False
self.break_now = True
def Worker(fn, work_queue, done_queue, done):
"""Worker to be run in a child process.
The worker stops on two conditions. 1. When the poison pill "STOP" is
reached or 2. when the event "done" is set."""
try:
for args in iter(work_queue.get, "STOP"):
if done.is_set():
break
try:
done_queue.put(NormalResult(fn(*args)))
except Exception, e:
print(">>> EXCEPTION: %s" % e)
done_queue.put(ExceptionResult())
except KeyboardInterrupt:
done_queue.put(BreakResult())
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):
self.num_workers = num_workers
self.processes = []
self.terminated = False
# Invariant: 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.count = 0
self.work_queue = Queue()
self.done_queue = Queue()
self.done = Event()
def imap_unordered(self, fn, gen):
"""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."""
try:
gen = iter(gen)
self.advance = self._advance_more
for w in xrange(self.num_workers):
p = Process(target=Worker, args=(fn,
self.work_queue,
self.done_queue,
self.done))
self.processes.append(p)
p.start()
self.advance(gen)
while self.count > 0:
result = self.done_queue.get()
self.count -= 1
if result.exception:
# Ignore items with unexpected exceptions.
continue
elif result.break_now:
# A keyboard interrupt happened in one of the worker processes.
raise KeyboardInterrupt
else:
yield result.result
self.advance(gen)
finally:
self.terminate()
def _advance_more(self, gen):
while self.count < self.num_workers * self.BUFFER_FACTOR:
try:
self.work_queue.put(gen.next())
self.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."""
self.work_queue.put(args)
self.count += 1
def terminate(self):
if self.terminated:
return
self.terminated = True
# For exceptional tear down set the "done" event to stop the workers before
# they empty the queue buffer.
self.done.set()
for p 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")
for p in self.processes:
p.join()
# Drain the queues to prevent failures 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