I'm try writing a netty plugin and have a cross threads problem I read doc
1. https://github.com/apache/incubator-skywalking/blob/5.x/docs/cn/Plugin-Development-Guide-CN.md#%E4%B8%89-contextsnapshot 2. https://github.com/apache/incubator-skywalking/blob/5.x/docs/en/Plugin-Development-Guide.md#contextsnapshot I capture a ContextSnapshot in another thread and continued ContextSnapshot in below codes: ```java public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes, MethodInterceptResult result) throws Throwable { ChannelHandlerContext context = (ChannelHandlerContext) allArguments[0]; Object msg = allArguments[1]; if (msg instanceof HttpRequest) { // Client Request System.out.println(">> " + Thread.currentThread().getId() + ":" + context.channel().hashCode()); Attribute<ContextSnapshot> attr = context.channel().attr(KEY_CONTEXT_SNAPSHOT); ContextSnapshot contextSnapshot = attr.get(); attr.set(null); if (contextSnapshot == null) { return; } ContextManager.continued(contextSnapshot); (Line: 45) HttpRequest request = (HttpRequest) msg; ContextCarrier contextCarrier = new ContextCarrier(); String uri = request.uri(); AbstractSpan span = ContextManager.createExitSpan(uri, contextCarrier, String.valueOf(context.channel().remoteAddress())); Tags.URL.set(span, request.uri()); Tags.HTTP.METHOD.set(span, request.method().name()); span.setComponent(COMPONENT_NETTY_HTTP_CLIENT); SpanLayer.asHttp(span); CarrierItem next = contextCarrier.items(); while (next.hasNext()) { next = next.next(); request.headers().set(next.getHeadKey(), next.getHeadValue()); } context.channel().attr(KEY_CONTEXT_SNAPSHOT).set(ContextManager.capture()); System.out.println("===> encode client request $$$$$$$$ " + Thread.currentThread().getId() + ":" + context.channel().hashCode()); } return; } ``` skywalking-api.log ： ``` ERROR 2018-09-26 17:29:56:913 InstMethodsInter : class[class io.netty.handler.codec.http.HttpClientCodec$Encoder] before method[encode] intercept failure java.lang.NullPointerException at org.apache.skywalking.apm.agent.core.context.ContextManager.capture(ContextManager.java:143) at org.apache.skywalking.apm.agent.core.context.ContextSnapshot.isFromCurrent(ContextSnapshot.java:119) at org.apache.skywalking.apm.agent.core.context.ContextManager.continued(ContextManager.java:150) at org.apache.skywalking.apm.plugin.netty.EncodeInterceptor.beforeMethod(EncodeInterceptor.java:45) at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:82) ``` how to resolve this situation？ [ Full content available at: https://github.com/apache/incubator-skywalking/issues/1706 ] This message was relayed via gitbox.apache.org for [email protected]
