Spring Plugin Maybe cause memory leak in some case

[IanCao]

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Spring Plugin Maybe cause memory leak in some case

org.apache.skywalking.apm.plugin.spring.mvc.commons.interceptor.AbstractMethodInterceptor

this is the key code.

the case is one @RequestMapping method(methodA) call other @RequestMapping method(methodB).

beforeMethodA--> methodA -> beforeMethodB -> methodB -> afterMethodB - >afterMethodA

beforeMethodA, a entry is creatted.
beforeMethodB, entry size++;
afterMethodB, entry size--(entry still in stack) & RESPONSE_KEY_IN_RUNTIME_CONTEXT removed.
afterMethodA, since RESPONSE_KEY_IN_RUNTIME_CONTEXT is null,return

all process has finished,but stack in thread is not empty.

[wu-sheng]

@IanCao Good catch. I have discussed with @ascrutae , we think we should

1. Add a stack-based flag in the running context.
2. Only create Entry Span when this flag does not exist.
3. Create Local Span when flag exists.
4. Clear running context(request/response) if flag is reset to 0.

What do you think?

[IanCao]

OK~~