[Python-checkins] bpo-45835: Fix race condition in test_queue (GH-29601) (GH-29612)
ambv
webhook-mailer at python.org
Thu Nov 18 11:05:50 EST 2021
https://github.com/python/cpython/commit/5cf05c71d13a4b4a94cc77da4214ee2f0b9c7de7
commit: 5cf05c71d13a4b4a94cc77da4214ee2f0b9c7de7
branch: 3.10
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: ambv <lukasz at langa.pl>
date: 2021-11-18T17:05:40+01:00
summary:
bpo-45835: Fix race condition in test_queue (GH-29601) (GH-29612)
Some of the tests in test_queue had a race condition in which a
non-sentinel value could be enqueued after the final sentinel value
leading to not all the inputs being processed (and test failures).
This changes feed() to enqueue a sentinel once the inputs are exhausted,
which guarantees that the final queued object is a sentinel. This
requires the number of feeder threads to match the number of consumer
threads, but that's already the case in the relevant tests.
(cherry picked from commit df3e53d86b2ad67da9ac2b5a3f56257d1f394982)
Co-authored-by: Sam Gross <colesbury at gmail.com>
files:
A Misc/NEWS.d/next/Tests/2021-11-17-14-28-08.bpo-45835.Mgyhjx.rst
M Lib/test/test_queue.py
diff --git a/Lib/test/test_queue.py b/Lib/test/test_queue.py
index 9bb5181377698..cfa6003a867da 100644
--- a/Lib/test/test_queue.py
+++ b/Lib/test/test_queue.py
@@ -420,11 +420,12 @@ class BaseSimpleQueueTest:
def setUp(self):
self.q = self.type2test()
- def feed(self, q, seq, rnd):
+ def feed(self, q, seq, rnd, sentinel):
while True:
try:
val = seq.pop()
except IndexError:
+ q.put(sentinel)
return
q.put(val)
if rnd.random() > 0.5:
@@ -463,11 +464,10 @@ def consume_timeout(self, q, results, sentinel):
return
results.append(val)
- def run_threads(self, n_feeders, n_consumers, q, inputs,
- feed_func, consume_func):
+ def run_threads(self, n_threads, q, inputs, feed_func, consume_func):
results = []
sentinel = None
- seq = inputs + [sentinel] * n_consumers
+ seq = inputs.copy()
seq.reverse()
rnd = random.Random(42)
@@ -481,11 +481,11 @@ def wrapper(*args, **kwargs):
return wrapper
feeders = [threading.Thread(target=log_exceptions(feed_func),
- args=(q, seq, rnd))
- for i in range(n_feeders)]
+ args=(q, seq, rnd, sentinel))
+ for i in range(n_threads)]
consumers = [threading.Thread(target=log_exceptions(consume_func),
args=(q, results, sentinel))
- for i in range(n_consumers)]
+ for i in range(n_threads)]
with threading_helper.start_threads(feeders + consumers):
pass
@@ -543,7 +543,7 @@ def test_order(self):
# Test a pair of concurrent put() and get()
q = self.q
inputs = list(range(100))
- results = self.run_threads(1, 1, q, inputs, self.feed, self.consume)
+ results = self.run_threads(1, q, inputs, self.feed, self.consume)
# One producer, one consumer => results appended in well-defined order
self.assertEqual(results, inputs)
@@ -553,7 +553,7 @@ def test_many_threads(self):
N = 50
q = self.q
inputs = list(range(10000))
- results = self.run_threads(N, N, q, inputs, self.feed, self.consume)
+ results = self.run_threads(N, q, inputs, self.feed, self.consume)
# Multiple consumers without synchronization append the
# results in random order
@@ -564,7 +564,7 @@ def test_many_threads_nonblock(self):
N = 50
q = self.q
inputs = list(range(10000))
- results = self.run_threads(N, N, q, inputs,
+ results = self.run_threads(N, q, inputs,
self.feed, self.consume_nonblock)
self.assertEqual(sorted(results), inputs)
@@ -574,7 +574,7 @@ def test_many_threads_timeout(self):
N = 50
q = self.q
inputs = list(range(1000))
- results = self.run_threads(N, N, q, inputs,
+ results = self.run_threads(N, q, inputs,
self.feed, self.consume_timeout)
self.assertEqual(sorted(results), inputs)
diff --git a/Misc/NEWS.d/next/Tests/2021-11-17-14-28-08.bpo-45835.Mgyhjx.rst b/Misc/NEWS.d/next/Tests/2021-11-17-14-28-08.bpo-45835.Mgyhjx.rst
new file mode 100644
index 0000000000000..6a73b01959065
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2021-11-17-14-28-08.bpo-45835.Mgyhjx.rst
@@ -0,0 +1 @@
+Fix race condition in test_queue tests with multiple "feeder" threads.
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