From: headius@headius.com
To: ruby-core@ruby-lang.org
Subject: [ruby-core:72155] [Ruby trunk - Bug #11822] Semantics of Queue#pop after close are wrong
Date: Tue, 15 Dec 2015 17:52:07 +0000 [thread overview]
Message-ID: <redmine.journal-55565.20151215175206.a3e2be5e55bbded9@ruby-lang.org> (raw)
In-Reply-To: redmine.issue-11822.20151215160530@ruby-lang.org
Issue #11822 has been updated by Charles Nutter.
Also worth noting that java.util.concurrent's BlockingQueue implementations do not support any of the following for the same reasons as above:
* Closing or shutting down a queue
* Notifying all threads waiting on a queue that it is no longer available
The justification is that shutdown semantics for threads waiting on a queue varies too greatly to have a single consistent semantic. Some code will want a "closed" queue to cause all waiters to raise an error, others may want them to all receive a null value, still others will want them to receive a poison pill indicating the queue is done. Basically, the expectation is that if user code sets up threads to wait on a queue, user code should also handle notifying them that the queue is no longer available for use.
I agree.
----------------------------------------
Bug #11822: Semantics of Queue#pop after close are wrong
https://bugs.ruby-lang.org/issues/11822#change-55565
* Author: Charles Nutter
* Status: Open
* Priority: Normal
* Assignee:
* ruby -v:
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
Current test/ruby/thread/test_queue.rb test_close has the following assertion that seems wrong to me:
def test_close
[->{Queue.new}, ->{SizedQueue.new 3}].each do |qcreate|
q = qcreate.call
assert_equal false, q.closed?
q << :something
assert_equal q, q.close
assert q.closed?
assert_raise_with_message(ClosedQueueError, /closed/){q << :nothing}
assert_equal q.pop, :something # <<< THIS ONE
assert_nil q.pop
assert_nil q.pop
# non-blocking
assert_raise_with_message(ThreadError, /queue empty/){q.pop(non_block=true)}
end
end
Once a queue is closed, I don't think it should ever return a result anymore. The queue should be cleared and pop should always return nil.
In r52691, ko1 states that "deq'ing on closed queue returns nil, always." This test does not match that behavior.
--
https://bugs.ruby-lang.org/
next prev parent reply other threads:[~2015-12-15 17:20 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <redmine.issue-11822.20151215160530@ruby-lang.org>
2015-12-15 16:05 ` [ruby-core:72149] [Ruby trunk - Bug #11822] [Open] Semantics of Queue#pop after close are wrong headius
2015-12-15 16:58 ` [ruby-core:72150] [Ruby trunk - Bug #11822] " headius
2015-12-15 17:48 ` [ruby-core:72152] " headius
2015-12-15 17:52 ` headius [this message]
2015-12-15 23:47 ` [ruby-core:72164] " ko1
2015-12-16 7:39 ` [ruby-core:72178] " funny.falcon
2015-12-18 5:32 ` [ruby-core:72357] " ko1
2015-12-18 18:41 ` [ruby-core:72369] " email
2015-12-19 1:39 ` [ruby-core:72372] " ko1
2015-12-19 13:37 ` [ruby-core:72380] " email
2015-12-19 14:37 ` [ruby-core:72382] " headius
2015-12-19 15:01 ` [ruby-core:72383] " email
2015-12-19 15:27 ` [ruby-core:72386] " headius
2015-12-19 15:29 ` [ruby-core:72387] " headius
2015-12-20 8:54 ` [ruby-core:72408] " funny.falcon
2016-01-25 18:21 ` [ruby-core:73429] " Andrew Vit
2017-01-31 7:12 ` [ruby-core:79334] [Ruby trunk Bug#11822][Closed] " ko1
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