[New-bugs-announce] [issue31145] PriorityQueue.put() fails with TypeError if priority_number in tuples of (priority_number, data) are the same.

[Mikołaj Babiak]

New submission from Mikołaj Babiak:

# list of tuples in form of (priority_number, data)
bugged = [
(-25.691, {'feedback': 13, 'sentiment': 0.309, 'support_ticket': 5}), (-25.691, {'feedback': 11, 'sentiment': 0.309, 'support_ticket': 3}), (-25.0, {'feedback': 23, 'sentiment': 0.0, 'support_ticket': 15}),
]

from queue import PriorityQueue

pq = PriorityQueue()

for item in bugged:
   pq.put(item)

# TypeError: '<' not supported between instances of 'dict' and 'dict'

It seems that if priority_numbers are equal, heapq.heapify() falls back to comparing data element from tuple (priority_number, data).
I belive this is an undesired behaviour.
It is acctually listed as one of implementation challenges on https://docs.python.org/3/library/heapq.html:
"Tuple comparison breaks for (priority, task) pairs if the priorities are equal and the tasks do not have a default comparison order."

In python 2.7 the issue in not present and PriorityQueue.put() works as expected

----------
components: Library (Lib)
messages: 299922
nosy: Mikołaj Babiak
priority: normal
severity: normal
status: open
title: PriorityQueue.put() fails with TypeError if priority_number in tuples of (priority_number, data) are the same.
type: behavior
versions: Python 3.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue31145>
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