Code review comment for lp:~abentley/launchpad/memlimit-sendbranchmail

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On 11-06-23 12:36 PM, Gavin Panella wrote:
> [1]
>
> + @staticmethod
> + def _register_subclass(cls):
> + """Register this class with its enumeration."""
> + # This would be a classmethod, except that subclasses (e.g.
> + # TranslationPackagingJob) need to be able to override it and call
> + # into it, and there's no syntax to call a base class's version of a
> + # classmethod with the subclass as the first parameter.
>
> I think super(BranchJobDerived, cls)._register_subclass() might work.

This doesn't work because _register_subclass is called before
BranchJobDerived is part of the global namespace (because it's called by
the metaclass).

class Bar(type):

    def __init__(cls, name, bases, dict_):
        cls.upcall()

class Foo(object):

    __metaclass__ = Bar

    @classmethod
    def upcall(cls):
        super(Foo, cls)

$ python superme.py
Traceback (most recent call last):
  File "superme.py", line 7, in <module>
    class Foo(object):
  File "superme.py", line 4, in __init__
    cls.upcall()
  File "superme.py", line 13, in upcall
    super(Foo, cls)
NameError: global name 'Foo' is not defined

> [2]
>
> +class BranchMailJobSource(BaseRunnableJobSource):
> + """Source of jobs that send mail about branches."""
> +
> + memory_limit = 2 * (1024 ** 3)
>
> 2GB is quite a high limit. Is that correct?

I'm using the limit applied to cronscripts/scan_branches.py (in 12991)
as an example. sendbranchmail runs on the same machine and uses similar
technology, including bzrlib.

The bug reports that 5GB is problematic, so this cuts it by more than half.

If you're wondering whether bzrlib really needs that much, well, it has
been quite memory-hungry historically, but I understand bzr 2.4 will be
a vast improvement.

Aaron
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