PI59999: OpenJPA custom plugins can cause Classloader leaks

Fixes are available

APAR status

Closed as program error.

Error description

When a customer creates a plugin, for example a JDBCListener
or DBDictionary, 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 Garbage Collected.
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.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  All users of IBM WebSphere Application      *
*                  Server V8.5.0 and V8.5.5 who make use of    *
*                  OpenJPA custom plugins.                     *
****************************************************************
* PROBLEM DESCRIPTION: OpenJPA custom plugins (for example,    *
*                      JDBCListener, DBDictionary) can cause   *
*                      Classloader leaks.                      *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When a customer creates an OpenJPA customer 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/ConcurrentReferenceHashMa
p 0x1110fa40
75,637,464 (59.42%) [64] 3 array of
org/apache/openjpa/lib/util/concurrent/ConcurrentReferenceHashMa
p$Entry 0x11115620
75,514,544 (59.32%) [48] 4
org/apache/openjpa/lib/util/concurrent/ConcurrentReferenceHashMa
p$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, the JDBCListener class (class
MyJDBCListener) is part of the leak suspect, with a retained
Configurations class. When looking at the OpenJPA
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 cause the
leak.

Problem conclusion

With this fix, code has been added to OpenJPA to ensure a
'weak' reference is made to the Configuration class, thus
allowing the custom plugin class to be GC'd after an
application restart.

The fix for this APAR is currently targeted for
inclusion in Service Level (Fix Pack) 8.5.5.10 of WebSphere
Application Server version 8.5.5 and Fix Pack 16.0.0.2 of Web
Liberty.

Please refer to the recommended updates page for delivery
information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PI59999
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
850
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2016-03-31
Closed date
2016-06-22
Last modified date
2016-06-27

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WEBS APP SERV N
Fixed component ID
5724H8800

Applicable component levels

R850 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.5","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
28 April 2022

Tips

PI59999: OpenJPA custom plugins can cause Classloader leaks

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R850 PSY

Document Information

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