alibaba/Sentinel

Reactor项目中使用Sentinel偶尔会出现Context0#put空指针异常

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#1907 opened on Dec 17, 2020

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area/integrationshelp wanted

Description

WebFlux项目中导入sentinel-spring-webflux-adapter:1.8.0适配模块，项目每天都有好几个NPE，报错内容如下：

Caused by: java.lang.NullPointerException: value
	at java.util.Objects.requireNonNull(Objects.java:228)
	at reactor.util.context.Context0.put(Context0.java:30)
	at com.alibaba.csp.sentinel.adapter.reactor.SentinelReactorSubscriber.currentContext(SentinelReactorSubscriber.java:70)

对应的源码应该是这一行

return actual.currentContext()
            .put(SentinelReactorConstants.SENTINEL_CONTEXT_KEY, currentEntry.getAsyncContext());

从异常栈信息看，应该是currentEntry.getAsyncContext()这句返回了null，但不知为何会出现null

Contributor guide

Tech stack
javaspring
Domain
backend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
JavaSpring WebFluxReactor fundamentals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Investigate the source code in SentinelReactorSubscriber.currentContext() at line 70. The null value from currentEntry.getAsyncContext() needs to be handled. Check if there are any existing PRs or comments addressing this. Determine if the null occurs due to async context not being set in some flow. Consider adding a null check and possibly using an empty context as fallback.