[ http://issues.apache.org/jira/browse/GERONIMO-1118?page=all ]
Dain Sundstrom reassigned GERONIMO-1118:
----------------------------------------
Assign To: Dain Sundstrom
> memory leak deploying web services caused by
> java.bean.Introspector.getBeanInfo()
> ---------------------------------------------------------------------------------
>
> Key: GERONIMO-1118
> URL: http://issues.apache.org/jira/browse/GERONIMO-1118
> Project: Geronimo
> Type: Bug
> Components: webservices
> Versions: 1.0
> Environment: Sun JDK 1.4.2/Win XP
> Reporter: Kevan Miller
> Assignee: Dain Sundstrom
> Attachments: IntrospectorFix.patch
>
> If you deploy and undeploy DayTrader several times, your server will run out
> of Permanent Generation space. I've tracked down a problem which is caused by
> java.bean.Introspector (there may be other problems, but it's hard to tell
> until this problem is fixed). The basic problem is described here --
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=5102804.
> To summarize, the static method java.bean.Introspector.getBeanInfo(Class)
> computes a BeanInfo object to describe the given Class. The computed BeanInfo
> data is cached in a WeakHashMap called "beanInfoCache". There's one fatal
> flaw in this approach. There's nothing "weak" at all about beanInfoCache. The
> key for the Map is the Class object. The value object is the BeanInfo data.
> Unfortunately, the BeanInfo data strongly references the Class. This strong
> reference will prevent the Class from being identified as available for GC
> via the WeakHashMap.
> Since java.bean.Introspector is loaded by the system class loader (and is
> thus a GC root), this means that Bean classes (e.g.
> org.apache.geronimo.samples.daytrader.client.ws.AccountDataBean), their
> MultiParentClassLoader, and all classes loaded by the MultiParentClassLoader
> will be kept alive until you kill your server...
> Luckily (or because of this problem?), Introspector also has flushCaches()
> and flushFromCaches(Class) methods which perform predictable functions.
> Several projects, including Tomcat and Spring, use these methods to prevent
> Introspector from causing memory leaks in their environments.
> Geronimo has the following usages of getBeanInfo()
> axis-builder/src/java/org/apache/geronimo/axis/builder/HeavyweightTypeInfoBuilder.java:389
> axis-builder/src/java/org/apache/geronimo/axis/builder/LightweightTypeInfoBuilder.java:131
> service-builder/src/java/org/apache/geronimo/deployment/service/JavaBeanXmlAttributeBuilder.java:66
> A non-scientific search (e.g. I don't have all the source), showed calls to
> Introspector.getBeanInfo() by the following projects:
> axis, cglib, commons-collections, tomcat (but calls flushCache), log4j
> I've thought of the following options for fixing this problem (alternative
> proposals welcome):
> 1. Follow all calls to getBeanInfo(Class) with a flushFromCaches(Class). This
> seems fragile and impractical (we can't insure that other projects/apps
> follow this rule).
> 2. Force java.Bean.Introspector to be loaded by MultiParentClassLoader. This
> would prevent the Introspector class from being a GC root. Would work, but is
> counter to the current class loader implementation...
> 3. Call Introspector.flushCaches() at appropriate times (i.e. when a
> ClassLoader is going out of scope -- when a GBean is stopped?). I need a
> little help here in knowing when/where this should be... Although this is a
> bit heavy-handed, it seems like a safe approach.
> 4. (just thought of this one). Instead of calling flushCaches() as described
> in 3, we could instead loop through all classes loaded by the appropriate
> MultiParentClassLoaders and call flushFromCaches(Class) (or a subset of the
> classes). This would work, but doesn't seem necessary. I doubt we have very
> much caching going on...
> I'll work on 3 and see how things improve...
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