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Re: mysql-connector-python starting from 8.0.12 goes to infinite loop when iterates till the end of table
Posted by: Alexey Chernov
Date: May 02, 2020 11:38AM

[djadm@probeg mainsite]$ ./ shell
Python 3.6.8 (default, Apr 2 2020, 13:34:55)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from results.models import *

>>> q1=Club.objects.all()
>>> q1.query
<django.db.models.sql.query.Query object at 0x7f6813cac588>
>>> print(q1.query)
SELECT `KLB1`.`IDKLB`, `KLB1`.`titul` FROM `KLB1`
>>> a=[x for x in q1]
[process killed after ~10 minutes of working with all available memory]

>>> q2=Club.objects.all()[:200]
>>> print(q2.query)
SELECT `KLB1`.`IDKLB`, `KLB1`.`titul` FROM `KLB1` LIMIT 200
>>> a=[x for x in q2]
[Finishes immediately]

>>> q3=Club.objects.all()[:201]
>>> q3.query
<django.db.models.sql.query.Query object at 0x7f56f5675860>
>>> print(q3.query)
SELECT `KLB1`.`IDKLB`, `KLB1`.`titul` FROM `KLB1` LIMIT 201
>>> a=[x for x in q3]
[I stopped it after ~30sec, the trace is below]

^CTraceback (most recent call last):
File "<console>", line 1, in <module>
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/models/", line 274, in __iter__
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/models/", line 1242, in _fetch_all
self._result_cache = list(self._iterable_class(self))
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/models/", line 55, in __iter__
results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/models/sql/", line 1173, in execute_sql
return list(result)
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/models/sql/", line 1552, in cursor_iter
for rows in iter((lambda: cursor.fetchmany(itersize)), sentinel):
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/models/sql/", line 1552, in <lambda>
for rows in iter((lambda: cursor.fetchmany(itersize)), sentinel):
File "/usr/local/venv/main/lib64/python3.6/site-packages/django/db/", line 96, in inner
return func(*args, **kwargs)
File "/usr/local/venv/main/lib64/python3.6/site-packages/mysql/connector/", line 511, in fetchmany
if size and self._cnx.unread_result:
File "/usr/local/venv/main/lib64/python3.6/site-packages/mysql/connector/", line 610, in unread_result
return self.result_set_available

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