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<a href="http://community.jboss.org/index.jspa" style="text-decoration: none; color: #E1E1E1">Community</a></h1>
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Classloading and caching changes
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reply from <a href="http://community.jboss.org/people/alesj">Ales Justin</a> in <i>JBoss Microcontainer Development</i> - <a href="http://community.jboss.org/message/543107#543107">View the full discussion</a>
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<div class="jive-rendered-content"><p>First a few questions.</p><blockquote class="jive-quote"><p>What's the idea behind "useLoadClassForParent" flag?<br/>* So, instead of going into that magic synch code, we try the parent before?</p></blockquote><p>The loadClassForParent is a backwards compatibility thing to work around<br/>a few issues that the more efficient resource check causes in some edge cases when it delegates to the java classpath.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>It shouldn't be using it when a Domain delegates to another Domain.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>That was something we spotted and fixed in 2.2.x, see around line old/new 689/920<br/><a class="jive-link-external-small" href="http://fisheye.jboss.org/browse/JBossAS/projects/jboss-cl/trunk/classloader/src/main/java/org/jboss/classloader/spi/ClassLoaderDomain.java?r1=95108&r2=96496" target="_blank">http://fisheye.jboss.org/browse/JBossAS/projects/jboss-cl/trunk/classloader/src/main/java/org/jboss/classloader/spi/ClassLoaderDomain.java?r1=95108&r2=96496</a></p><blockquote class="jive-quote"><p>Why doesn't this code write into global cache?<br/>* I guess only certain Loaders are valid for caching? e.g. depending on the policy or "OSGi" rules<br/><br/>(from BaseClassLoaderDomain)<br/><br/>Loader loader = findLoader(classLoader, path, allExports, findInParent);<br/>     if (loader != null)<br/>     {<br/>        Thread thread = Thread.currentThread();<br/>        ClassLoadingTask task = new ClassLoadingTask(name, classLoader, thread);<br/>        ClassLoaderManager.scheduleTask(task, loader, false);<br/>        Class<?> result = ClassLoaderManager.process(thread, task);<br/>        ClassCacheItem item = globalClassCache.get(path);<br/>        if (item != null)<br/>           item.clazz = result;<br/>        return result;<br/>     }</p></blockquote><p>Whether it caches things is decided elsewhere, based on the ClassLoaderPolicy rules.<br/>This code is just a safety check in the event that the class changes <br/>(somebody redeployed a classloader) and the global cache hasn't been flushed properly.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>As I said on the other response, it can't cache the load in that "globalClassCache", because<br/>the classloader used is in the parent domain. It would need some complicated<br/>flushing rules to cache it in the child domain as well - not my preferred solution.</p></div>
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