view roundup/anypy/cmp_.py @ 6565:2c2dbfc332ba

Try to handle multiple connections better. The session database is a hot spot. When multiple requests (e.g. 20) come in at the same time session database contention can get great. The original code didn't retry session database access when the open failed. This resulted in errors at the client. The second pass delayed 0.01 seconds and retried. It was better but we still had multiple second stalls. I think the first request got in, everybody else backed up and then retried at the same time. Again they stepped on each other. With logging I would see many counters go all the way to low single digits or to -1 indicating falure. This pass uses randomint to generate delays from 0-.125 seconds in 5ms increments. This performs better in testing. I rarely saw a counter less than 13 (2 failed retries). Current logging starts after 6 failures and counts down until success or failure.
author John Rouillard <rouilj@ieee.org>
date Thu, 16 Dec 2021 20:02:00 -0500
parents 142553f58694
children 706f3be6ffbb
line wrap: on
line source

try:
    None < 0

    def NoneAndDictComparable(v):
        return v
except TypeError:
    # comparator to allow comparisons against None and dict
    # comparisons (these were allowed in Python 2, but aren't allowed
    # in Python 3 any more)
    class NoneAndDictComparable(object):
        def __init__(self, value):
            self.value = value

        def __cmp__(self, other):
            if not isinstance(other, self.__class__):
                raise TypeError('not comparable')

            if self.value == other.value:
                return 0

            elif self.value is None:
                return -1

            elif other.value is None:
                return 1

            elif type(self.value) == tuple and type(other.value) == tuple:
                for lhs, rhs in zip(self.value, other.value):
                    lhsCmp = NoneAndDictComparable(lhs)
                    rhsCmp = NoneAndDictComparable(rhs)
                    result = lhsCmp.__cmp__(rhsCmp)
                    if result != 0:
                        return result

                return len(self.value) - len(other.value)

            elif type(self.value) == dict and type(other.value) == dict:
                diff = len(self.value) - len(other.value)
                if diff == 0:
                    lhsItems = tuple(sorted(self.value.items(),
                                            key=NoneAndDictComparable))
                    rhsItems = tuple(sorted(other.value.items(),
                                            key=NoneAndDictComparable))
                    return -1 if NoneAndDictComparable(lhsItems) < NoneAndDictComparable(rhsItems) else 1
                else:
                    return diff

            elif self.value < other.value:
                return -1

            else:
                return 1

        def __eq__(self, other):
            return self.__cmp__(other) == 0

        def __ne__(self, other):
            return self.__cmp__(other) != 0

        def __lt__(self, other):
            return self.__cmp__(other) < 0

        def __le__(self, other):
            return self.__cmp__(other) <= 0

        def __ge__(self, other):
            return self.__cmp__(other) >= 0

        def __gt__(self, other):
            return self.__cmp__(other) > 0


def _test():
    Comp = NoneAndDictComparable

    assert Comp(None) < Comp(0)
    assert Comp(None) < Comp('')
    assert Comp(None) < Comp({})
    assert Comp((0, None)) < Comp((0, 0))
    assert not Comp(0) < Comp(None)
    assert not Comp('') < Comp(None)
    assert not Comp({}) < Comp(None)
    assert not Comp((0, 0)) < Comp((0, None))

    assert Comp((0, 0)) < Comp((0, 0, None))
    assert Comp((0, None, None)) < Comp((0, 0, 0))

    assert Comp(0) < Comp(1)
    assert Comp(1) > Comp(0)
    assert not Comp(1) < Comp(0)
    assert not Comp(0) > Comp(0)

    assert Comp({0: None}) < Comp({0: 0})
    assert Comp({0: 0}) < Comp({0: 1})

    assert Comp({0: 0}) == Comp({0: 0})
    assert Comp({0: 0}) != Comp({0: 1})
    assert Comp({0: 0, 1: 1}) > Comp({0: 1})
    assert Comp({0: 0, 1: 1}) < Comp({0: 0, 2: 2})


if __name__ == '__main__':
    _test()

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