SSH项目运行中出现内存溢出，求解决方案，谢谢！

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系统是由struts2 + spring2 + hibernate3 + freemarker + compass + oscache构建的，经常运行一段时间后，总是出现内存溢出问题。现在主要是这个问题不知道如何解决，请求各位帮忙！

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2011-10-21 16:28:55 org.apache.catalina.core.StandardWrapperValve invoke
严重: Servlet.service() for servlet default threw exception
java.lang.OutOfMemoryError: Java heap space
??? at sun.text.UCompactIntArray.initPlane(UCompactIntArray.java:142)
??? at sun.text.UCompactIntArray.setElementAt(UCompactIntArray.java:55)
??? at java.text.RBTableBuilder.addOrder(RBTableBuilder.java:324)
??? at java.text.RBTableBuilder.addComposedChars(RBTableBuilder.java:194)
??? at java.text.RBTableBuilder.build(RBTableBuilder.java:140)
??? at java.text.RBCollationTables.<init>(RBCollationTables.java:65)
??? at java.text.RuleBasedCollator.<init>(RuleBasedCollator.java:276)
??? at java.text.Collator.getInstance(Collator.java:251)
??? at freemarker.core.Environment.getCollator(Environment.java:737)
??? at freemarker.core.ComparisonExpression.isTrue(ComparisonExpression.java:165)
??? at freemarker.core.ParentheticalExpression.isTrue(ParentheticalExpression.java:66)
??? at freemarker.core.ConditionalBlock.accept(ConditionalBlock.java:77)
??? at freemarker.core.Environment.visit(Environment.java:210)
??? at freemarker.core.MixedContent.accept(MixedContent.java:92)
??? at freemarker.core.Environment.visit(Environment.java:210)
??? at freemarker.core.IfBlock.accept(IfBlock.java:82)
??? at freemarker.core.Environment.visit(Environment.java:210)
??? at freemarker.core.IteratorBlock$Context.runLoop(IteratorBlock.java:167)
??? at freemarker.core.Environment.visit(Environment.java:417)
??? at freemarker.core.IteratorBlock.accept(IteratorBlock.java:102)
??? at freemarker.core.Environment.visit(Environment.java:210)
??? at freemarker.core.MixedContent.accept(MixedContent.java:92)
??? at freemarker.core.Environment.visit(Environment.java:210)
??? at freemarker.core.Environment.process(Environment.java:190)
??? at freemarker.template.Template.process(Template.java:237)
??? at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:748)
??? at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:505)
??? at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
??? at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
??? at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
??? at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
??? at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:198)