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TypeError when f_trace is None and tracing. #64240

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xdegaye mannequin opened this issue Dec 21, 2013 · 8 comments
Closed

TypeError when f_trace is None and tracing. #64240

xdegaye mannequin opened this issue Dec 21, 2013 · 8 comments
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@serhiy-storchaka
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interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error

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@xdegaye
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Mannequin

xdegaye mannequin commented Dec 21, 2013

BPO 20041
Nosy @birkenfeld, @abalkin, @xdegaye, @serhiy-storchaka, @nightlark
Files
  • tracer.py
  • f_trace.patch
  • tests.patch
  • none_f_trace.patch
    		•

    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/serhiy-storchaka'
closed_at = <Date 2016-06-04.17:34:11.251>
created_at = <Date 2013-12-21.14:01:27.004>
labels = ['interpreter-core', 'type-bug']
title = 'TypeError when f_trace is None and tracing.'
updated_at = <Date 2021-08-18.06:37:50.621>
user = 'https://github.com/xdegaye'

    bugs.python.org fields:

    activity = <Date 2021-08-18.06:37:50.621>
actor = 'rmast'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-06-04.17:34:11.251>
closer = 'serhiy.storchaka'
components = ['Interpreter Core']
creation = <Date 2013-12-21.14:01:27.004>
creator = 'xdegaye'
dependencies = []
files = ['33245', '33246', '33260', '43198']
hgrepos = []
issue_num = 20041
keywords = ['patch']
message_count = 8.0
messages = ['206735', '206896', '267094', '267157', '267158', '267265', '267281', '267288']
nosy_count = 7.0
nosy_names = ['georg.brandl', 'belopolsky', 'xdegaye', 'python-dev', 'serhiy.storchaka', 'Winterflower', 'rmast']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue20041'
versions = ['Python 3.5', 'Python 3.6']
    @xdegaye
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    xdegaye mannequin commented Dec 21, 2013

    Section 3.2 of 'The Python Language Reference' states:
    f_trace, if not None, is a function called at the start of each source code line

    Run the attached tracer.py and see that although f_trace is None in both cases when 'cmd' is either
'delete' or 'set', the second case raises a TypeError exception:
$ python tracer.py
f_trace: None
delete start
delete done
f_trace: None
set start
Traceback (most recent call last):
  File "tracer.py", line 19, in <module>
    foo('set')
  File "tracer.py", line 15, in foo
    print(cmd, 'done')
  File "tracer.py", line 15, in foo
    print(cmd, 'done')
TypeError: 'NoneType' object is not callable

    Also, the frame.f_lineno may be wrong in a traceback when f_trace is set to None because
    PyFrame_GetLineNumber() does not handle this case.

    The attached patch fixes this issue.
    The patch also fixes bpo-11992 and bpo-20040.
    The patch also fixes the dispatch_call() method of Bdb in the bdb module when the frame is a
    generator and the previous command is next, until or return.
    The patch also provides a backward compatible solution to the performance enhancement described in
    bpo-16672.

    @xdegaye xdegaye mannequin added interpreter-core (Objects, Python, Grammar, and Parser dirs) type-bug An unexpected behavior, bug, or error labels Dec 21, 2013
    @xdegaye
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    xdegaye mannequin commented Dec 24, 2013

    Adding the corresponding tests.

    @xdegaye xdegaye mannequin added topic-2to3 interpreter-core (Objects, Python, Grammar, and Parser dirs) and removed interpreter-core (Objects, Python, Grammar, and Parser dirs) topic-2to3 labels Dec 24, 2013
    @serhiy-storchaka
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    I think the code would be simpler if convert the argument of frame_settrace() to NULL if it is Py_None.

    @xdegaye
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    xdegaye mannequin commented Jun 3, 2016

    On a 'call' trace event, the bdb dispatch_call() function returns None when there is nothing to trace in this function (no breakpoints). With the changes made by the patch in ceval.c, the costly maybe_call_line_trace() function is not called on each line in this case since f->f_trace is Py_None. This provides the performance enhancements described in bpo-16672 without breaking the _hotshot extension module or other extension modules using PyEval_SetTrace().

    I agree that the code would be much simpler when f->f_trace is set to NULL by the frame_settrace() setter or trace_trampoline() when it is Py_None. The performance gain described above by using Py_None may not be worth the complexity.

    Thanks for looking into this Serhiy.

    @serhiy-storchaka
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    This may be worthwhile optimization, but this is different issue. Let first fix a TypeError, and then open new issue for the optimization.

    @xdegaye
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    xdegaye mannequin commented Jun 4, 2016

    This patch fixes the TypeError.
    New bpo-27218: improve tracing performance with f_trace set to Py_None.

    @serhiy-storchaka
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    LGTM.

    @serhiy-storchaka serhiy-storchaka self-assigned this Jun 4, 2016
    @python-dev
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    python-dev mannequin commented Jun 4, 2016

    New changeset 4d916be61d46 by Serhiy Storchaka in branch '2.7':
    Issue bpo-20041: Fixed TypeError when frame.f_trace is set to None.
    https://hg.python.org/cpython/rev/4d916be61d46

    New changeset 74ad78d2dd8d by Serhiy Storchaka in branch '3.5':
    Issue bpo-20041: Fixed TypeError when frame.f_trace is set to None.
    https://hg.python.org/cpython/rev/74ad78d2dd8d

    New changeset f993dbeb2ad2 by Serhiy Storchaka in branch 'default':
    Issue bpo-20041: Fixed TypeError when frame.f_trace is set to None.
    https://hg.python.org/cpython/rev/f993dbeb2ad2

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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