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  1. JDK
  2. JDK-8273790

Potential cyclic dependencies between Gregorian and CalendarSystem

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    • b17
    • generic
    • generic
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        We find cyclic dependencies between Gregorian and CalendarSystem classes in our test environment when using JDK11 AOT(It also affects JDK tip).

        The class hierarchies are as follows(w/ some simplifications):

        ```
        class GregorianCalendar {
        static Gregorian base = CalendarSystem.getGregorianCalendar();
        }

        class Gregorian extends BaseCalendar { }
        class BaseCalendar extends AbstractCalendar {}
        class AbstractCalendar extends CalendarSystem {}

        public class CalendarSystem {
        Gregorian GREGORIAN_INSTANCE = new Gregorian();
        }
        ```

        We create two new threads to link GregorianCalendar and AbstractCalendar, respectively.

        T1: new GregorianCalendar()
        GregorianCalendar -> Gregorian -> BaseCalendar -> AbstractCalendar -> CalendarSystem

        T2: Unsafe.ensureInitialized(AbstractCalendar.class)
        AbstractCalendar -> CalendarSystem -> Gregorian

        What would next happen, is that application hanging due to deadlock between inGregorian and AbstractCalendar.

          1. aothang2.txt
            39 kB
          2. aothang.txt
            83 kB

              jpai Jaikiran Pai
              yyang Yi Yang
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