711 lines
22 KiB
Python
711 lines
22 KiB
Python
# Copyright (c) Twisted Matrix Laboratories.
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# See LICENSE for details.
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"""
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Tests for L{twisted.python.threadpool}
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"""
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import gc
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import pickle
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import threading
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import time
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import weakref
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from twisted._threads import Team, createMemoryWorker
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from twisted.python import context, failure, threadable, threadpool
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from twisted.trial import unittest
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class Synchronization:
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failures = 0
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def __init__(self, N, waiting):
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self.N = N
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self.waiting = waiting
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self.lock = threading.Lock()
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self.runs = []
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def run(self):
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# This is the testy part: this is supposed to be invoked
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# serially from multiple threads. If that is actually the
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# case, we will never fail to acquire this lock. If it is
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# *not* the case, we might get here while someone else is
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# holding the lock.
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if self.lock.acquire(False):
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if not len(self.runs) % 5:
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# Constant selected based on empirical data to maximize the
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# chance of a quick failure if this code is broken.
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time.sleep(0.0002)
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self.lock.release()
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else:
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self.failures += 1
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# This is just the only way I can think of to wake up the test
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# method. It doesn't actually have anything to do with the
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# test.
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self.lock.acquire()
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self.runs.append(None)
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if len(self.runs) == self.N:
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self.waiting.release()
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self.lock.release()
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synchronized = ["run"]
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threadable.synchronize(Synchronization)
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class ThreadPoolTests(unittest.SynchronousTestCase):
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"""
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Test threadpools.
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"""
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def getTimeout(self):
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"""
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Return number of seconds to wait before giving up.
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"""
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return 5 # Really should be order of magnitude less
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def _waitForLock(self, lock):
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items = range(1000000)
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for i in items:
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if lock.acquire(False):
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break
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time.sleep(1e-5)
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else:
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self.fail("A long time passed without succeeding")
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def test_attributes(self):
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"""
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L{ThreadPool.min} and L{ThreadPool.max} are set to the values passed to
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L{ThreadPool.__init__}.
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"""
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pool = threadpool.ThreadPool(12, 22)
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self.assertEqual(pool.min, 12)
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self.assertEqual(pool.max, 22)
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def test_start(self):
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"""
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L{ThreadPool.start} creates the minimum number of threads specified.
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"""
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pool = threadpool.ThreadPool(0, 5)
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pool.start()
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self.addCleanup(pool.stop)
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self.assertEqual(len(pool.threads), 0)
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pool = threadpool.ThreadPool(3, 10)
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self.assertEqual(len(pool.threads), 0)
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pool.start()
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self.addCleanup(pool.stop)
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self.assertEqual(len(pool.threads), 3)
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def test_adjustingWhenPoolStopped(self):
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"""
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L{ThreadPool.adjustPoolsize} only modifies the pool size and does not
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start new workers while the pool is not running.
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"""
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pool = threadpool.ThreadPool(0, 5)
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pool.start()
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pool.stop()
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pool.adjustPoolsize(2)
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self.assertEqual(len(pool.threads), 0)
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def test_threadCreationArguments(self):
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"""
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Test that creating threads in the threadpool with application-level
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objects as arguments doesn't results in those objects never being
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freed, with the thread maintaining a reference to them as long as it
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exists.
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"""
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tp = threadpool.ThreadPool(0, 1)
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tp.start()
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self.addCleanup(tp.stop)
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# Sanity check - no threads should have been started yet.
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self.assertEqual(tp.threads, [])
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# Here's our function
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def worker(arg):
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pass
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# weakref needs an object subclass
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class Dumb:
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pass
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# And here's the unique object
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unique = Dumb()
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workerRef = weakref.ref(worker)
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uniqueRef = weakref.ref(unique)
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# Put some work in
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tp.callInThread(worker, unique)
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# Add an event to wait completion
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event = threading.Event()
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tp.callInThread(event.set)
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event.wait(self.getTimeout())
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del worker
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del unique
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gc.collect()
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self.assertIsNone(uniqueRef())
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self.assertIsNone(workerRef())
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def test_threadCreationArgumentsCallInThreadWithCallback(self):
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"""
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As C{test_threadCreationArguments} above, but for
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callInThreadWithCallback.
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"""
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tp = threadpool.ThreadPool(0, 1)
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tp.start()
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self.addCleanup(tp.stop)
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# Sanity check - no threads should have been started yet.
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self.assertEqual(tp.threads, [])
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# this holds references obtained in onResult
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refdict = {} # name -> ref value
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onResultWait = threading.Event()
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onResultDone = threading.Event()
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resultRef = []
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# result callback
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def onResult(success, result):
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# Spin the GC, which should now delete worker and unique if it's
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# not held on to by callInThreadWithCallback after it is complete
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gc.collect()
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onResultWait.wait(self.getTimeout())
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refdict["workerRef"] = workerRef()
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refdict["uniqueRef"] = uniqueRef()
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onResultDone.set()
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resultRef.append(weakref.ref(result))
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# Here's our function
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def worker(arg, test):
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return Dumb()
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# weakref needs an object subclass
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class Dumb:
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pass
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# And here's the unique object
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unique = Dumb()
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onResultRef = weakref.ref(onResult)
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workerRef = weakref.ref(worker)
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uniqueRef = weakref.ref(unique)
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# Put some work in
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tp.callInThreadWithCallback(onResult, worker, unique, test=unique)
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del worker
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del unique
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# let onResult collect the refs
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onResultWait.set()
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# wait for onResult
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onResultDone.wait(self.getTimeout())
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gc.collect()
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self.assertIsNone(uniqueRef())
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self.assertIsNone(workerRef())
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# XXX There's a race right here - has onResult in the worker thread
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# returned and the locals in _worker holding it and the result been
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# deleted yet?
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del onResult
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gc.collect()
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self.assertIsNone(onResultRef())
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self.assertIsNone(resultRef[0]())
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# The callback shouldn't have been able to resolve the references.
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self.assertEqual(list(refdict.values()), [None, None])
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def test_persistence(self):
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"""
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Threadpools can be pickled and unpickled, which should preserve the
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number of threads and other parameters.
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"""
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pool = threadpool.ThreadPool(7, 20)
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self.assertEqual(pool.min, 7)
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self.assertEqual(pool.max, 20)
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# check that unpickled threadpool has same number of threads
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copy = pickle.loads(pickle.dumps(pool))
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self.assertEqual(copy.min, 7)
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self.assertEqual(copy.max, 20)
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def _threadpoolTest(self, method):
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"""
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Test synchronization of calls made with C{method}, which should be
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one of the mechanisms of the threadpool to execute work in threads.
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"""
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# This is a schizophrenic test: it seems to be trying to test
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# both the callInThread()/dispatch() behavior of the ThreadPool as well
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# as the serialization behavior of threadable.synchronize(). It
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# would probably make more sense as two much simpler tests.
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N = 10
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tp = threadpool.ThreadPool()
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tp.start()
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self.addCleanup(tp.stop)
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waiting = threading.Lock()
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waiting.acquire()
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actor = Synchronization(N, waiting)
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for i in range(N):
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method(tp, actor)
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self._waitForLock(waiting)
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self.assertFalse(actor.failures, f"run() re-entered {actor.failures} times")
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def test_callInThread(self):
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"""
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Call C{_threadpoolTest} with C{callInThread}.
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"""
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return self._threadpoolTest(lambda tp, actor: tp.callInThread(actor.run))
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def test_callInThreadException(self):
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"""
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L{ThreadPool.callInThread} logs exceptions raised by the callable it
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is passed.
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"""
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class NewError(Exception):
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pass
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def raiseError():
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raise NewError()
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThread(raiseError)
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tp.start()
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tp.stop()
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errors = self.flushLoggedErrors(NewError)
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self.assertEqual(len(errors), 1)
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def test_callInThreadWithCallback(self):
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"""
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L{ThreadPool.callInThreadWithCallback} calls C{onResult} with a
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two-tuple of C{(True, result)} where C{result} is the value returned
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by the callable supplied.
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"""
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waiter = threading.Lock()
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waiter.acquire()
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results = []
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def onResult(success, result):
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waiter.release()
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results.append(success)
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results.append(result)
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThreadWithCallback(onResult, lambda: "test")
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tp.start()
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try:
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self._waitForLock(waiter)
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finally:
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tp.stop()
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self.assertTrue(results[0])
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self.assertEqual(results[1], "test")
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def test_callInThreadWithCallbackExceptionInCallback(self):
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"""
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L{ThreadPool.callInThreadWithCallback} calls C{onResult} with a
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two-tuple of C{(False, failure)} where C{failure} represents the
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exception raised by the callable supplied.
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"""
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class NewError(Exception):
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pass
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def raiseError():
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raise NewError()
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waiter = threading.Lock()
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waiter.acquire()
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results = []
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def onResult(success, result):
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waiter.release()
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results.append(success)
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results.append(result)
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThreadWithCallback(onResult, raiseError)
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tp.start()
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try:
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self._waitForLock(waiter)
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finally:
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tp.stop()
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self.assertFalse(results[0])
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self.assertIsInstance(results[1], failure.Failure)
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self.assertTrue(issubclass(results[1].type, NewError))
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def test_callInThreadWithCallbackExceptionInOnResult(self):
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"""
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L{ThreadPool.callInThreadWithCallback} logs the exception raised by
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C{onResult}.
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"""
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class NewError(Exception):
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pass
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waiter = threading.Lock()
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waiter.acquire()
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results = []
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def onResult(success, result):
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results.append(success)
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results.append(result)
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raise NewError()
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThreadWithCallback(onResult, lambda: None)
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tp.callInThread(waiter.release)
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tp.start()
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try:
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self._waitForLock(waiter)
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finally:
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tp.stop()
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errors = self.flushLoggedErrors(NewError)
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self.assertEqual(len(errors), 1)
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self.assertTrue(results[0])
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self.assertIsNone(results[1])
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def test_callbackThread(self):
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"""
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L{ThreadPool.callInThreadWithCallback} calls the function it is
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given and the C{onResult} callback in the same thread.
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"""
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threadIds = []
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event = threading.Event()
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def onResult(success, result):
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threadIds.append(threading.current_thread().ident)
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event.set()
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def func():
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threadIds.append(threading.current_thread().ident)
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThreadWithCallback(onResult, func)
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tp.start()
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self.addCleanup(tp.stop)
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event.wait(self.getTimeout())
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self.assertEqual(len(threadIds), 2)
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self.assertEqual(threadIds[0], threadIds[1])
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def test_callbackContext(self):
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"""
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The context L{ThreadPool.callInThreadWithCallback} is invoked in is
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shared by the context the callable and C{onResult} callback are
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invoked in.
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"""
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myctx = context.theContextTracker.currentContext().contexts[-1]
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myctx["testing"] = "this must be present"
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contexts = []
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event = threading.Event()
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def onResult(success, result):
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ctx = context.theContextTracker.currentContext().contexts[-1]
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contexts.append(ctx)
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event.set()
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def func():
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ctx = context.theContextTracker.currentContext().contexts[-1]
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contexts.append(ctx)
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThreadWithCallback(onResult, func)
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tp.start()
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self.addCleanup(tp.stop)
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event.wait(self.getTimeout())
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self.assertEqual(len(contexts), 2)
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self.assertEqual(myctx, contexts[0])
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self.assertEqual(myctx, contexts[1])
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def test_existingWork(self):
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"""
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Work added to the threadpool before its start should be executed once
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the threadpool is started: this is ensured by trying to release a lock
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previously acquired.
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"""
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waiter = threading.Lock()
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waiter.acquire()
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tp = threadpool.ThreadPool(0, 1)
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tp.callInThread(waiter.release) # Before start()
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tp.start()
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try:
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self._waitForLock(waiter)
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finally:
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tp.stop()
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def test_workerStateTransition(self):
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"""
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As the worker receives and completes work, it transitions between
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the working and waiting states.
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"""
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pool = threadpool.ThreadPool(0, 1)
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pool.start()
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self.addCleanup(pool.stop)
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# Sanity check
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self.assertEqual(pool.workers, 0)
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self.assertEqual(len(pool.waiters), 0)
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self.assertEqual(len(pool.working), 0)
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# Fire up a worker and give it some 'work'
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threadWorking = threading.Event()
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threadFinish = threading.Event()
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def _thread():
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threadWorking.set()
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threadFinish.wait(10)
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pool.callInThread(_thread)
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threadWorking.wait(10)
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self.assertEqual(pool.workers, 1)
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self.assertEqual(len(pool.waiters), 0)
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self.assertEqual(len(pool.working), 1)
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# Finish work, and spin until state changes
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threadFinish.set()
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while not len(pool.waiters):
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time.sleep(0.0005)
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# Make sure state changed correctly
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self.assertEqual(len(pool.waiters), 1)
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self.assertEqual(len(pool.working), 0)
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def test_q(self) -> None:
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"""
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There is a property '_queue' for legacy purposes
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"""
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pool = threadpool.ThreadPool(0, 1)
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self.assertEqual(pool._queue.qsize(), 0)
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class RaceConditionTests(unittest.SynchronousTestCase):
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def setUp(self):
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self.threadpool = threadpool.ThreadPool(0, 10)
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self.event = threading.Event()
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self.threadpool.start()
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def done():
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self.threadpool.stop()
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del self.threadpool
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self.addCleanup(done)
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def getTimeout(self):
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"""
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A reasonable number of seconds to time out.
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"""
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return 5
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def test_synchronization(self):
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"""
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If multiple threads are waiting on an event (via blocking on something
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in a callable passed to L{threadpool.ThreadPool.callInThread}), and
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there is spare capacity in the threadpool, sending another callable
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which will cause those to un-block to
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L{threadpool.ThreadPool.callInThread} will reliably run that callable
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and un-block the blocked threads promptly.
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@note: This is not really a unit test, it is a stress-test. You may
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need to run it with C{trial -u} to fail reliably if there is a
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problem. It is very hard to regression-test for this particular
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bug - one where the thread pool may consider itself as having
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"enough capacity" when it really needs to spin up a new thread if
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it possibly can - in a deterministic way, since the bug can only be
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provoked by subtle race conditions.
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"""
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timeout = self.getTimeout()
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self.threadpool.callInThread(self.event.set)
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self.event.wait(timeout)
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self.event.clear()
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for i in range(3):
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self.threadpool.callInThread(self.event.wait)
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self.threadpool.callInThread(self.event.set)
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self.event.wait(timeout)
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if not self.event.isSet():
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self.event.set()
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self.fail("'set' did not run in thread; timed out waiting on 'wait'.")
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class MemoryPool(threadpool.ThreadPool):
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"""
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A deterministic threadpool that uses in-memory data structures to queue
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work rather than threads to execute work.
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"""
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def __init__(self, coordinator, failTest, newWorker, *args, **kwargs):
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"""
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Initialize this L{MemoryPool} with a test case.
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@param coordinator: a worker used to coordinate work in the L{Team}
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underlying this threadpool.
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@type coordinator: L{twisted._threads.IExclusiveWorker}
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@param failTest: A 1-argument callable taking an exception and raising
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a test-failure exception.
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@type failTest: 1-argument callable taking (L{Failure}) and raising
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|
L{unittest.FailTest}.
|
|
|
|
@param newWorker: a 0-argument callable that produces a new
|
|
L{twisted._threads.IWorker} provider on each invocation.
|
|
@type newWorker: 0-argument callable returning
|
|
L{twisted._threads.IWorker}.
|
|
"""
|
|
self._coordinator = coordinator
|
|
self._failTest = failTest
|
|
self._newWorker = newWorker
|
|
threadpool.ThreadPool.__init__(self, *args, **kwargs)
|
|
|
|
def _pool(self, currentLimit, threadFactory):
|
|
"""
|
|
Override testing hook to create a deterministic threadpool.
|
|
|
|
@param currentLimit: A 1-argument callable which returns the current
|
|
threadpool size limit.
|
|
|
|
@param threadFactory: ignored in this invocation; a 0-argument callable
|
|
that would produce a thread.
|
|
|
|
@return: a L{Team} backed by the coordinator and worker passed to
|
|
L{MemoryPool.__init__}.
|
|
"""
|
|
|
|
def respectLimit():
|
|
# The expression in this method copied and pasted from
|
|
# twisted.threads._pool, which is unfortunately bound up
|
|
# with lots of actual-threading stuff.
|
|
stats = team.statistics()
|
|
if (stats.busyWorkerCount + stats.idleWorkerCount) >= currentLimit():
|
|
return None
|
|
return self._newWorker()
|
|
|
|
team = Team(
|
|
coordinator=self._coordinator,
|
|
createWorker=respectLimit,
|
|
logException=self._failTest,
|
|
)
|
|
return team
|
|
|
|
|
|
class PoolHelper:
|
|
"""
|
|
A L{PoolHelper} constructs a L{threadpool.ThreadPool} that doesn't actually
|
|
use threads, by using the internal interfaces in L{twisted._threads}.
|
|
|
|
@ivar performCoordination: a 0-argument callable that will perform one unit
|
|
of "coordination" - work involved in delegating work to other threads -
|
|
and return L{True} if it did any work, L{False} otherwise.
|
|
|
|
@ivar workers: the workers which represent the threads within the pool -
|
|
the workers other than the coordinator.
|
|
@type workers: L{list} of 2-tuple of (L{IWorker}, C{workPerformer}) where
|
|
C{workPerformer} is a 0-argument callable like C{performCoordination}.
|
|
|
|
@ivar threadpool: a modified L{threadpool.ThreadPool} to test.
|
|
@type threadpool: L{MemoryPool}
|
|
"""
|
|
|
|
def __init__(self, testCase, *args, **kwargs):
|
|
"""
|
|
Create a L{PoolHelper}.
|
|
|
|
@param testCase: a test case attached to this helper.
|
|
|
|
@type args: The arguments passed to a L{threadpool.ThreadPool}.
|
|
|
|
@type kwargs: The arguments passed to a L{threadpool.ThreadPool}
|
|
"""
|
|
coordinator, self.performCoordination = createMemoryWorker()
|
|
self.workers = []
|
|
|
|
def newWorker():
|
|
self.workers.append(createMemoryWorker())
|
|
return self.workers[-1][0]
|
|
|
|
self.threadpool = MemoryPool(
|
|
coordinator, testCase.fail, newWorker, *args, **kwargs
|
|
)
|
|
|
|
def performAllCoordination(self):
|
|
"""
|
|
Perform all currently scheduled "coordination", which is the work
|
|
involved in delegating work to other threads.
|
|
"""
|
|
while self.performCoordination():
|
|
pass
|
|
|
|
|
|
class MemoryBackedTests(unittest.SynchronousTestCase):
|
|
"""
|
|
Tests using L{PoolHelper} to deterministically test properties of the
|
|
threadpool implementation.
|
|
"""
|
|
|
|
def test_workBeforeStarting(self):
|
|
"""
|
|
If a threadpool is told to do work before starting, then upon starting
|
|
up, it will start enough workers to handle all of the enqueued work
|
|
that it's been given.
|
|
"""
|
|
helper = PoolHelper(self, 0, 10)
|
|
n = 5
|
|
for x in range(n):
|
|
helper.threadpool.callInThread(lambda: None)
|
|
helper.performAllCoordination()
|
|
self.assertEqual(helper.workers, [])
|
|
helper.threadpool.start()
|
|
helper.performAllCoordination()
|
|
self.assertEqual(len(helper.workers), n)
|
|
|
|
def test_tooMuchWorkBeforeStarting(self):
|
|
"""
|
|
If the amount of work before starting exceeds the maximum number of
|
|
threads allowed to the threadpool, only the maximum count will be
|
|
started.
|
|
"""
|
|
helper = PoolHelper(self, 0, 10)
|
|
n = 50
|
|
for x in range(n):
|
|
helper.threadpool.callInThread(lambda: None)
|
|
helper.performAllCoordination()
|
|
self.assertEqual(helper.workers, [])
|
|
helper.threadpool.start()
|
|
helper.performAllCoordination()
|
|
self.assertEqual(len(helper.workers), helper.threadpool.max)
|