Heath Thomann created OPENJPA-2636:
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Summary: Custom plugins (e.g. JDBCListener, DBDictionary) can
cause Classloader leaks.
Key: OPENJPA-2636
URL: https://issues.apache.org/jira/browse/OPENJPA-2636
Project: OpenJPA
Issue Type: Bug
Components: jdbc
Affects Versions: 2.2.3, 2.4.2
Reporter: Heath Thomann
Assignee: Heath Thomann
Priority: Minor
When a customer creates a plugin, for example a JDBCListener, there exists the
possibility for the custom JDBCListener to retain a reference to a Classloader,
which in turn will not allow the Classloader to be GC'd. For example, when the
JDBCListener is part of a JEE application and the application is restarted, the
JDBCListener class can be listed as as a leak suspect, as follows in this leak
suspect stack:
75,675,296 (59.45%) [32] 67 class
org/apache/openjpa/kernel/AbstractBrokerFactory 0x1027f7e8
|- 75,637,832 (59.42%) [32] 40 class org/apache/openjpa/lib/conf/Configurations
0xf370b48
|- 75,637,552 (59.42%) [64] 2
org/apache/openjpa/lib/util/concurrent/ConcurrentReferenceHashMap 0x1110fa40
|- 75,637,464 (59.42%) [64] 3 array of
org/apache/openjpa/lib/util/concurrent/ConcurrentReferenceHashMap$Entry
0x11115620
|- 75,514,544 (59.32%) [48] 4
org/apache/openjpa/lib/util/concurrent/ConcurrentReferenceHashMap$WeakEntry
0x1111edb0
|- 75,514,496 (59.32%) [48] 1
java/util/concurrent/ConcurrentHashMap 0x111f47b8
|- 75,514,448 (59.32%) [80] 16 array of
java/util/concurrent/ConcurrentHashMap$Segment 0x111f47e8
|- 75,505,976 (59.32%) [32] 2
java/util/concurrent/ConcurrentHashMap$Segment 0x111f48d0
|- 75,505,912 (59.32%) [24] 1 array of
java/util/concurrent/ConcurrentHashMap$HashEntry 0x110d8f08
|- 75,505,888 (59.32%) [24] 2
java/util/concurrent/ConcurrentHashMap$HashEntry 0x110d8f18
|- 75,505,752 (59.32%) [32] 18 class
listener/MyJDBCListener 0x10296078
|- 75,505,600 (59.31%) [48] 1 java/util/HashMap
0x11113f88
|- 75,505,552 (59.31%) [65,552] 6,411 array of
java/util/HashMap$Entry 0x1401ed10
As can be seen in this stack, my JDBCListener (class MyJDBCListener) is part of
the leak suspect, with a retained Configurations class. When looking at the
Configurations class, it can be seen that the Configurations class has a
ConcurrentReferenceHashMap which contains a Classloader to Map, where the Map
contains the JDBCListener class (MyJDBCListener). It is these two maps which
causes the leak.
Thanks,
Heath
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