Is it too late in Python 3.4 release process to add a new method to classes of the tracemalloc module?

Here is a patch which adds unit tests and uses the new method in the documentation.

Example before:

    Top 10 lines
    #1: collections/__init__.py:368: 291.9 KiB
    #2: Lib/doctest.py:1291: 200.2 KiB
    #3: unittest/case.py:571: 160.3 KiB
    #4: Lib/abc.py:133: 99.8 KiB
    #5: urllib/parse.py:476: 71.8 KiB
    #6: <string>:5: 62.7 KiB
    #7: Lib/base64.py:140: 59.8 KiB
    #8: Lib/_weakrefset.py:37: 51.8 KiB
    #9: collections/__init__.py:362: 50.6 KiB
    #10: test/test_site.py:56: 48.0 KiB
    7496 other: 4161.9 KiB
    Total allocated size: 5258.8 KiB

Example after:

    Top 10 lines
    #1: Lib/base64.py:414: 419.8 KiB
        _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
    #2: Lib/base64.py:306: 419.8 KiB
        _a85chars2 = [(a + b) for a in _a85chars for b in _a85chars]
    #3: collections/__init__.py:368: 293.6 KiB
        exec(class_definition, namespace)
    #4: Lib/abc.py:133: 115.2 KiB
        cls = super().__new__(mcls, name, bases, namespace)
    #5: unittest/case.py:574: 103.1 KiB
        testMethod()
    #6: Lib/linecache.py:127: 95.4 KiB
        lines = fp.readlines()
    #7: urllib/parse.py:476: 71.8 KiB
        for a in _hexdig for b in _hexdig}
    #8: <string>:5: 62.0 KiB
    #9: Lib/_weakrefset.py:37: 60.0 KiB
        self.data = set()
    #10: Lib/base64.py:142: 59.8 KiB
        _b32tab2 = [a + b for a in _b32tab for b in _b32tab]
    6220 other: 3602.8 KiB
    Total allocated size: 5303.1 KiB

The getline() is convinient.

Sorry for being late, but the need of the new method came when I started to work again on tracemalloc to prepare my conference for Pycon US.

Yes it is too late.  The only reason any code changes should be made to the final RC is if we would otherwise have a brown bag release.

New changeset 14c1ff6a8086 by Victor Stinner in branch 'default':
Issue #20888: improve "Pretty Top" example of tracemalloc, use linecache
http://hg.python.org/cpython/rev/14c1ff6a8086

The method name should be "get_line", not "getline", to conform to the PEP 8.

It's not very useful to add an helper to the Traceback, it's more interesting to add it to the Trace class. So linecache.getline(trace.traceback[0].filename, trace.traceback[0].lineno) just becomes trace.get_line().

I updated the patch: tracemalloc_get_line-2.patch.

> Yes it is too late.

Ok. I applied to most interesting change (on the documentation) for Python 3.4.1.

About the patch, is it a bad thing to add new methods (get_line) to such debug module in a minor version (3.4.1)? It can be surprising if sometimes try the same code on Python 3.4.1 and 3.4.0.

Well, the proposed addition is just an helper, linecache can still used ;-) It's just convinient to write "one-shot" script (use and delete) using tracemalloc.

The policy is clear, no API additions in micro releases (the only exceptions should be made for security issues).

Ok, I prefer to develop this feature is tools based on tracemalloc and wait later to add this feature if it is still needed.