You are viewing a plain text version of this content. The canonical link for it is here.
Posted to notifications@skywalking.apache.org by GitBox <gi...@apache.org> on 2018/09/26 09:38:17 UTC
[GitHub] otyyyywangwenbin opened a new issue #1706: Netty Client跨线程 ContextManager.continued出现空指针
otyyyywangwenbin opened a new issue #1706: Netty Client跨线程 ContextManager.continued出现空指针
URL: https://github.com/apache/incubator-skywalking/issues/1706
参照文档
https://github.com/apache/incubator-skywalking/blob/5.x/docs/cn/Plugin-Development-Guide-CN.md#%E4%B8%89-contextsnapshot
```
当发生一次A->B的跨线程调用时：
需要在A线程中通过ContextManager#capture操作生成ContextSnapshot对象实例
将这个ContextSnapshot对象传递到B线程中
B线程通过ContextManager#continued操作完成上下文传递
```
代码如下
```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);
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;
}
```
代码第45行执行时出错，错误如下：
```
ERROR 2018-09-26 17:29:56:913 InstMethodsInter : class[class io.netty.handler.codec.http.HttpClientCodec$Encoder] before method[encode] intercept failure-
java.lang.NullPointerException
>---at org.apache.skywalking.apm.agent.core.context.ContextManager.capture(ContextManager.java:143)
>---at org.apache.skywalking.apm.agent.core.context.ContextSnapshot.isFromCurrent(ContextSnapshot.java:119)
>---at org.apache.skywalking.apm.agent.core.context.ContextManager.continued(ContextManager.java:150)
>---at org.apache.skywalking.apm.plugin.netty.EncodeInterceptor.beforeMethod(EncodeInterceptor.java:45)
>---at org.apache.skywalking.apm.agent.core.plugin.interceptor.enhance.InstMethodsInter.intercept(InstMethodsInter.java:82)
>---at io.netty.handler.codec.http.HttpObjectEncoder.encode(HttpObjectEncoder.java)
>---at io.netty.handler.codec.http.HttpClientCodec$Encoder.encode(HttpClientCodec.java:167)
>---at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:88)
>---at io.netty.channel.CombinedChannelDuplexHandler.write(CombinedChannelDuplexHandler.java:348)
>---at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:738)
>---at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:730)
>---at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:816)
>---at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:723)
>---at reactor.ipc.netty.channel.ChannelOperationsHandler.doWrite(ChannelOperationsHandler.java:290)
>---at reactor.ipc.netty.channel.ChannelOperationsHandler.drain(ChannelOperationsHandler.java:464)
>---at reactor.ipc.netty.channel.ChannelOperationsHandler.flush(ChannelOperationsHandler.java:192)
>---at io.netty.channel.AbstractChannelHandlerContext.invokeFlush0(AbstractChannelHandlerContext.java:776)
>---at io.netty.channel.AbstractChannelHandlerContext.invokeWriteAndFlush(AbstractChannelHandlerContext.java:802)
>---at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:814)
>---at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:794)
>---at io.netty.channel.AbstractChannelHandlerContext.writeAndFlush(AbstractChannelHandlerContext.java:831)
>---at io.netty.channel.DefaultChannelPipeline.writeAndFlush(DefaultChannelPipeline.java:1071)
>---at io.netty.channel.AbstractChannel.writeAndFlush(AbstractChannel.java:300)
>---at reactor.ipc.netty.http.HttpOperations.lambda$then$0(HttpOperations.java:135)
>---at reactor.ipc.netty.FutureMono$DeferredFutureMono.subscribe(FutureMono.java:197)
>---at reactor.core.publisher.Mono.subscribe(Mono.java:3080)
>---at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.drain(MonoIgnoreThen.java:172)
>---at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:56)
>---at reactor.core.publisher.Mono.subscribe(Mono.java:3080)
>---at reactor.ipc.netty.NettyOutbound.subscribe(NettyOutbound.java:354)
>---at reactor.core.publisher.MonoSource.subscribe(MonoSource.java:51)
>---at reactor.ipc.netty.channel.ChannelOperations.applyHandler(ChannelOperations.java:380)
>---at reactor.ipc.netty.http.client.HttpClientOperations.onHandlerStart(HttpClientOperations.java:503)
>---at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
>---at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:404)
>---at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:464)
>---at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:884)
>---at java.lang.Thread.run(Thread.java:745)
```
请问该如何解决？
----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on GitHub and use the
URL above to go to the specific comment.
For queries about this service, please contact Infrastructure at:
users@infra.apache.org
With regards,
Apache Git Services