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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DERBY-5730) DataDictionaryImpl leaks references to itself via SYSFUN_AD
Date Fri, 27 Apr 2012 08:55:58 GMT
Knut Anders Hatlen created DERBY-5730:

             Summary: DataDictionaryImpl leaks references to itself via SYSFUN_AD
                 Key: DERBY-5730
                 URL: https://issues.apache.org/jira/browse/DERBY-5730
             Project: Derby
          Issue Type: Bug
          Components: Services
    Affects Versions:
            Reporter: Knut Anders Hatlen

DataDictionaryImpl contains a static field called SYSFUN_AD, which holds an array of AliasDescriptor
objects for the functions in the SYSFUN schema. This array is lazily populated as the functions
are called, and it is shared between all DataDictionaryImpl instances on the system.

The AliasDescriptors contain references to the DataDictionaryImpl that created them, so SYSFUN_AD
may end up referencing indirectly to a number of different DataDictionaryImpl instances, depending
on where the respective SYSFUN functions are called the first time. Once an AliasDescriptor
has been added to SYSFUN_AD, it stays there until the DataDictionaryImpl class is unloaded
(in most cases, until the JVM terminates). This means the array may hold references to DataDictionaryImpl
instances that belong to database instances that have been shut down, and that the memory
held by those database instances never becomes eligible for garbage collection.

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