Python reinitialization test

[tiran]

BPO	1977
Nosy	@loewis, @pitrou, @tiran
Superseder	bpo-10914: Python sub-interpreter test
Files	test_reinit.patch test_reinit.c

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/pitrou'
closed_at = <Date 2012-11-26.20:00:28.290>
created_at = <Date 2008-01-30.19:10:43.009>
labels = ['interpreter-core', 'type-feature', 'build']
title = 'Python reinitialization test'
updated_at = <Date 2012-11-26.20:00:28.288>
user = 'https://github.com/tiran'

bugs.python.org fields:

activity = <Date 2012-11-26.20:00:28.288>
actor = 'pitrou'
assignee = 'pitrou'
closed = True
closed_date = <Date 2012-11-26.20:00:28.290>
closer = 'pitrou'
components = ['Build', 'Interpreter Core']
creation = <Date 2008-01-30.19:10:43.009>
creator = 'christian.heimes'
dependencies = []
files = ['9334', '9339']
hgrepos = []
issue_num = 1977
keywords = ['patch']
message_count = 12.0
messages = ['61873', '61875', '61876', '61895', '61899', '61904', '83564', '116941', '116958', '126329', '176420', '176448']
nosy_count = 4.0
nosy_names = ['loewis', 'pitrou', 'christian.heimes', 'BreamoreBoy']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = None
status = 'closed'
superseder = '10914'
type = 'enhancement'
url = 'https://bugs.python.org/issue1977'
versions = ['Python 3.2']

[tiran]

The patch adds a new test and a new executable. The executable calls
Py_Initialze() and Py_Finalize() multiple times in a row. The test also
shows that Python looses about 35 references in each round.

$ ./test_reinit
round 1
[7751 refs]
round 2
[7797 refs]
round 3
[7834 refs]
round 4
[7871 refs]
round 5
[7908 refs]
round 6
[7945 refs]
round 7
[7982 refs]
round 8
[8019 refs]
round 9
[8056 refs]
round 10
[8093 refs]

[loewis]

I'm not sure what the purpose of this test is. When would it pass, when
would it fail? I don't think it is a bug if a
Py_Initialize()/Py_Finalize() cycle loses references.

[tiran]

Martin v. Löwis wrote:

Martin v. Löwis added the comment:

I'm not sure what the purpose of this test is. When would it pass, when
would it fail? I don't think it is a bug if a
Py_Initialize()/Py_Finalize() cycle loses references.

Today my attempts to fix some reference leaks related to sys.flags and
sys.float_info caused the test to fail. A single init/final cycle worked
but the second cycle broke.

The test also shows an issue in Python 3.0. The double linked reference
list is broken:

$ ./test_reinit
round 1
[24676 refs]
round 2
[25588 refs]
round 3
* ob
object  : <refcnt 0 at 0x82248e8>
type    : str
refcount: 0
address : 0x82248e8
* op->_ob_prev->_ob_next
object  : <refcnt 0 at 0x82248e8>
type    : str
refcount: 0
address : 0x82248e8
* op->_ob_next->_ob_prev
object  : bytearray(b'')
type    : bytearray
refcount: 1
address : 0x839ab98
Fatal Python error: UNREF invalid object
Aborted (core dumped)

[pitrou]

Perhaps ROUNDS, CAUSE_SEGFAULT and VERBOSE could be command-line rather
than compile-time options?

[tiran]

I like to keep the test as simple as possible.

Here is a new file that shows Python crashes in the third Py_Finalize().

[tiran]

If fixed the problem with multiple reinitialization in r60477. It took
me quite some time to find the right spot.

[pitrou]

This is still a good idea.

[BreamoreBoy]

Quote msg83564 "This is still a good idea.", in which case shouldn't someone push this forward, failing that close as out of date?

[pitrou]

Quote msg83564 "This is still a good idea.", in which case shouldn't
someone push this forward, failing that close as out of date?

Just because someone doesn't "push this forward" doesn't mean it's out of date.

[pitrou]

See also bpo-10914.

[tiran]

Antoine, is the test still required? bpo-10914 has introduced tests for the subinterpreter.

[pitrou]

Ah, funny. I ended up doing the same thing as you without remembering about it!