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ScouterClassWriter에서 자바 기본 클래스 로딩에 실패하는 현상 #809

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codingstore opened this issue Aug 4, 2021 · 1 comment
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ScouterClassWriter에서 자바 기본 클래스 로딩에 실패하는 현상 #809

codingstore opened this issue Aug 4, 2021 · 1 comment
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자바 에이전트에서 NPE가 발생하는 경우가 확인되어 리포팅합니다.

  private StringBuffer typeAncestors(String type, ClassReader info) throws IOException {
    StringBuffer b = new StringBuffer();
    while (!"java/lang/Object".equals(type)) {
      b.append(';').append(type);
      type = info.getSuperName();
      info = typeInfo(type);
    } 
    return b;
  }

자바 기본 클래스 (예시에서는 java.util.Properties)를 extend하는 클래스를 상위로 타고 올라가는 경우
typeInfo에서 null이 리턴되어 getSuperName 호출 시 null pointer exception이 발생합니다.

  private ClassReader typeInfo(String type) throws IOException {
    ClassLoader loader = AgentTransformer.hookingCtx.get();
    InputStream is = null;
    try {
      if (loader == null) {
        is = ClassLoader.getSystemResourceAsStream(type + ".class");
      } else {
    	//java/lang/object, java/util/Properties 등 기본클래스 로드시 null이 리턴
        is = loader.getResourceAsStream(type + ".class");
        //임시 우회 코드
        if(is == null){
        	is = ClassLoader.getSystemResourceAsStream(type + ".class");
        }
      } 
      if (is == null)
        return null; 
      return new ClassReader(is);
    } finally {
      if (is != null)
        is.close(); 
    } 
  }
20210804 13:09:03 [A101] Transformer Error : com/tmax/proobject/engine/servicemanager/thread/ServiceWorkerThread
java.lang.NullPointerException
        scouter.agent.asm.ScouterClassWriter.typeAncestors(ScouterClassWriter.java:127)
        scouter.agent.asm.ScouterClassWriter.getCommonSuperClass(ScouterClassWriter.java:81)
        scouter.org.objectweb.asm.SymbolTable.addMergedType(SymbolTable.java:1202)
        scouter.org.objectweb.asm.Frame.merge(Frame.java:1299)
        scouter.org.objectweb.asm.Frame.merge(Frame.java:1197)
        scouter.org.objectweb.asm.MethodWriter.computeAllFrames(MethodWriter.java:1610)
        scouter.org.objectweb.asm.MethodWriter.visitMaxs(MethodWriter.java:1546)
        scouter.agent.asm.ServiceMV.visitMaxs(ServiceASM.java:353)
        scouter.org.objectweb.asm.ClassReader.readCode(ClassReader.java:2636)
        scouter.org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1488)
        scouter.org.objectweb.asm.ClassReader.accept(ClassReader.java:718)
        scouter.org.objectweb.asm.ClassReader.accept(ClassReader.java:401)
        scouter.agent.AgentTransformer.transform(AgentTransformer.java:263)
        sun.instrument.TransformerManager.transform(TransformerManager.java:188)
        sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:428)
        java.lang.ClassLoader.defineClass1(Native Method)
        java.lang.ClassLoader.defineClass(ClassLoader.java:763)
        jeus.service.archive.ArchiveClassLoader.defineClass(ArchiveClassLoader.java:607)
        jeus.service.archive.ArchiveClassLoader.findClass0(ArchiveClassLoader.java:461)
        jeus.servlet.loader.ContextLoader.findClass0(ContextLoader.java:131)
        jeus.service.archive.ArchiveClassLoader.loadClassWithoutDelegation(ArchiveClassLoader.java:351)
        jeus.service.archive.ArchiveArrayClassLoader.loadClass(ArchiveArrayClassLoader.java:358)
        jeus.servlet.loader.ContextLoader.loadClass(ContextLoader.java:223)
        java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.instantiationServiceWorkerThread(ServiceWorkerThreadPool.java:176)
        com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.createServiceWorkerThread(ServiceWorkerThreadPool.java:149)
        com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.initializePool(ServiceWorkerThreadPool.java:112)
        com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.(ServiceWorkerThreadPool.java:93)
        com.tmax.proobject.engine.servicemanager.ServiceGroupManager.runWorkerThread(ServiceGroupManager.java:457)
        com.tmax.proobject.engine.servicemanager.ServiceGroupManager.activate(ServiceGroupManager.java:452)
        com.tmax.proobject.engine.application.ApplicationManager.activateServiceGroup(ApplicationManager.java:1007)
        com.tmax.proobject.engine.application.ApplicationManager.activate(ApplicationManager.java:775)
        com.tmax.proobject.engine.application.ApplicationManager.run(ApplicationManager.java:219)
        com.tmax.proobject.engine.event.po.eventhandler.ProObjectReadyEventHandler.onEvent(ProObjectReadyEventHandler.java:69)
        com.tmax.proobject.model.event.EventHandler.handleEvent(EventHandler.java:64)
        com.tmax.proobject.engine.event.po.EventLoopProcessor.executeLoop(EventLoopProcessor.java:165)
        com.tmax.proobject.engine.event.po.EventLoopProcessor.run(EventLoopProcessor.java:86)
        jeus.io.impl.nio.NIOSelector.run(NIOSelector.java:534)
        java.lang.Thread.run(Thread.java:748)
java.lang.NullPointerException
        at scouter.agent.asm.ScouterClassWriter.typeAncestors(ScouterClassWriter.java:127)
        at scouter.agent.asm.ScouterClassWriter.getCommonSuperClass(ScouterClassWriter.java:81)
        at scouter.org.objectweb.asm.SymbolTable.addMergedType(SymbolTable.java:1202)
        at scouter.org.objectweb.asm.Frame.merge(Frame.java:1299)
        at scouter.org.objectweb.asm.Frame.merge(Frame.java:1197)
        at scouter.org.objectweb.asm.MethodWriter.computeAllFrames(MethodWriter.java:1610)
        at scouter.org.objectweb.asm.MethodWriter.visitMaxs(MethodWriter.java:1546)
        at scouter.agent.asm.ServiceMV.visitMaxs(ServiceASM.java:353)
        at scouter.org.objectweb.asm.ClassReader.readCode(ClassReader.java:2636)
        at scouter.org.objectweb.asm.ClassReader.readMethod(ClassReader.java:1488)
        at scouter.org.objectweb.asm.ClassReader.accept(ClassReader.java:718)
        at scouter.org.objectweb.asm.ClassReader.accept(ClassReader.java:401)
        at scouter.agent.AgentTransformer.transform(AgentTransformer.java:263)
        at sun.instrument.TransformerManager.transform(TransformerManager.java:188)
        at sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:428)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
        at jeus.service.archive.ArchiveClassLoader.defineClass(ArchiveClassLoader.java:607)
        at jeus.service.archive.ArchiveClassLoader.findClass0(ArchiveClassLoader.java:461)
        at jeus.servlet.loader.ContextLoader.findClass0(ContextLoader.java:131)
        at jeus.service.archive.ArchiveClassLoader.loadClassWithoutDelegation(ArchiveClassLoader.java:351)
        at jeus.service.archive.ArchiveArrayClassLoader.loadClass(ArchiveArrayClassLoader.java:358)
        at jeus.servlet.loader.ContextLoader.loadClass(ContextLoader.java:223)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
        at com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.instantiationServiceWorkerThread(ServiceWorkerThreadPool.java:176)
        at com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.createServiceWorkerThread(ServiceWorkerThreadPool.java:149)
        at com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.initializePool(ServiceWorkerThreadPool.java:112)
        at com.tmax.proobject.engine.servicemanager.thread.ServiceWorkerThreadPool.(ServiceWorkerThreadPool.java:93)
        at com.tmax.proobject.engine.servicemanager.ServiceGroupManager.runWorkerThread(ServiceGroupManager.java:457)
        at com.tmax.proobject.engine.servicemanager.ServiceGroupManager.activate(ServiceGroupManager.java:452)
        at com.tmax.proobject.engine.application.ApplicationManager.activateServiceGroup(ApplicationManager.java:1007)
        at com.tmax.proobject.engine.application.ApplicationManager.activate(ApplicationManager.java:775)
        at com.tmax.proobject.engine.application.ApplicationManager.run(ApplicationManager.java:219)
        at com.tmax.proobject.engine.event.po.eventhandler.ProObjectReadyEventHandler.onEvent(ProObjectReadyEventHandler.java:69)
        at com.tmax.proobject.model.event.EventHandler.handleEvent(EventHandler.java:64)
        at com.tmax.proobject.engine.event.po.EventLoopProcessor.executeLoop(EventLoopProcessor.java:165)
        at com.tmax.proobject.engine.event.po.EventLoopProcessor.run(EventLoopProcessor.java:86)
        at jeus.io.impl.nio.NIOSelector.run(NIOSelector.java:534)
        at java.lang.Thread.run(Thread.java:748)

임의로 null 리턴 시 시스템 리소스에서 로딩해보도록 테스트를 해 보았는데
에러가 발생하지 않는것같습니다.

참고부탁드립니다
@gunlee01 gunlee01 self-assigned this Aug 5, 2021
@gunlee01
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gunlee01 commented Sep 6, 2021

감사합니다. 다음 버전에 적용 예정입니다.

@gunlee01 gunlee01 closed this as completed Sep 6, 2021
gunlee01 added a commit that referenced this issue Sep 6, 2021
@gunlee01
[agent.java] issue '#809' 반영
72535b3
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@gunlee01 @codingstore