skywalking: NPE Aspect

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Why do you submit this issue?
Question or discussion
Bug
Requirement
Feature or performance improvement

Question

What do you want to know? Isn’t this bug solved? issue #1114 Does this edition still have this problem

Bug

Which version of SkyWalking, OS and JRE? apache-skywalking-apm-6.1.0 Centos，MacOS JRE1.8
Which company or project?
What happen? If possible, provide a way for reproducing the error. e.g. demo application, component version. `@Pointcut(“execution(public * com.lea.scm.web….(…))”) public void log() { }

@Before(“log()”) public void exBefore(JoinPoint joinPoint) { ServletRequestAttributes sra = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes(); HttpServletRequest request = sra.getRequest(); logger.info(“url:” + request.getRequestURL()); logger.info(“method:” + request.getMethod()); logger.info(“class method:” + joinPoint.getSignature().getDeclaringTypeName() + “.” + joinPoint.getSignature().getName()); if(!ObjectUtils.isEmpty(joinPoint.getArgs())){ logger.info(“args:” + JsonUtils.toJson(joinPoint.getArgs())); } }`

java.lang.NullPointerException: null at com.lea.scm.web.GoodsExternalController.shopGoodsListPage$original$TiDS4VBn(GoodsExternalController.java:110) at com.lea.scm.web.GoodsExternalController.shopGoodsListPage$original$TiDS4VBn$accessor$M9qsnZ2l(GoodsExternalController.java) at com.lea.scm.web.GoodsExternalController$auxiliary$VfxWxE5S.call(Unknown Source) at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:93) at com.lea.scm.web.GoodsExternalController.shopGoodsListPage(GoodsExternalController.java) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest$original$YWb59KLP(InvocableHandlerMethod.java:133) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest$original$YWb59KLP$accessor$43vOj5WC(InvocableHandlerMethod.java) at org.springframework.web.method.support.InvocableHandlerMethod$auxiliary$dFEFp2LA.call(Unknown Source) at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:93) at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java) at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827) at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738) at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:872) at javax.servlet.http.HttpServlet.service(HttpServlet.java:661) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846) at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.boot.web.filter.ApplicationContextHeaderFilter.doFilterInternal(ApplicationContextHeaderFilter.java:55) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.boot.actuate.trace.WebRequestTraceFilter.doFilterInternal(WebRequestTraceFilter.java:111) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:105) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.cloud.sleuth.instrument.web.TraceFilter.doFilter(TraceFilter.java:166) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:197) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.springframework.boot.actuate.autoconfigure.MetricsFilter.doFilterInternal(MetricsFilter.java:103) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:493) at org.apache.catalina.core.StandardHostValve.invoke$original$NsgxOShB(StandardHostValve.java:140) at org.apache.catalina.core.StandardHostValve.invoke$original$NsgxOShB$accessor$zQGbHoR0(StandardHostValve.java) at org.apache.catalina.core.StandardHostValve$auxiliary$CrZwynl4.call(Unknown Source) at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:93) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:800) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:806) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1498) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:748)

Requirement or improvement

Please describe about your requirements or improvement suggestions.

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 15 (12 by maintainers)

Most upvoted comments

Actually, this is a complex problem. 1.the controller method modifier is private which is not recommend for controller, without skywalking agent it is working just because an accident, you can try add a public method in the controller ,you will see the goodsExternalService is always null in private method. 1.1 why the goodsExternalService is always null in private method if add another public method? the reason is the controller is enhanced by cglib in spring ,in enhanced classes ,private method cannot get goodsExternalService 1.2 why it can work in current version? the reason is the controller just have a method and is private and it is not match the ascpect expression ,so the controller will not be enhanced by cglib in spring .

2.why with skywalking agent it doesn’t work? the reason is is have implement an interface EnhanceInstance and it have two default method getSkywalkingField and setSkywalkingField which modifier is public ,this match the aspect expression.so the controller will enhanced by cglib in spring .

3.conclusion If the class is enhanced by cglib in spring .all private method will get goodsExternalService by null.

candyleer on Jul 11, 2019

spring-boot-starter-aop:2.1.1.RELEAS

@SpringBootApplication
public class AopApplication implements CommandLineRunner {

    public static void main(String[] args) {
        SpringApplication.run(AopApplication.class);
    }

    @Autowired
    private Service service;

    @Override
    public void run(String... args) throws Exception {
        System.out.println("autowired:" + System.identityHashCode(service));

        Method method1 = Service.class.getDeclaredMethod("method1");
        method1.setAccessible(true);
        method1.invoke(service);

        Method method2 = Service.class.getDeclaredMethod("method2");
        method2.setAccessible(true);
        method2.invoke(service);
    }
}
@Aspect
@Component
public class AopAspect {

    @Pointcut("execution(* com.github.sunnus3.example.spring.Service.*(..))")
    public void aop() {

    }

    @Before("aop()")
    public void before(JoinPoint joinPoint) {
        System.out.println("before ...");
    }
}
@Component
public class Service {


    private void method1() {
        System.out.println("private method: " + System.identityHashCode(this));
    }

    public void method2() {
        System.out.println("public  method: " + System.identityHashCode(this));
    }
}

Result
autowired:680988889
private method: 680988889
before ...
public  method: 1792227359

arugal on Jul 12, 2019

So for your case,I recommend you to update the controller method to public modifier will resolve this problem. actually ,public modifier for controller ReqeustMapping method should be best practice.

If the application work with agent should work as same as work without agent, I think we should not implement EnhanceInstance interface. but this should be long discussed.

candyleer on Jul 11, 2019