When skywalking-go is set to a low sampling rate, such as: sample (0.5), there is a problem of sharing ctx (GetGLS()). You need to manually call tracing.CleanContext() in AfterInvoke.

[Donghui0]

If multiple HTTP requests share the same goroutine, will the previous ctx be obtained?
for example:
First request: Unsampled
GET /hello (entrySpan) (NoopSpan)
|
GET /h1 (exitSpan) (NoopSpan)

Second request:
There may be the same goroutine, and the createEntrySpan() -> t.createNoop() -> getTracingContext() method retrieves the NoopSpan stored in the first request.

Currently, the tracing.CleanContext() call is added to the afterInvoke method in the gin plugin.
Is there any problem with doing this? Why do you need to call this method explicitly?

[wu-sheng]

@mrproliu Could you check this?

[mrproliu]

Currently, For the NoopSpan, there is no reference count yet and GLS continues to be occupied. this is a bug.

[mrproliu]

I will try to fix it recently.

[wu-sheng]

This should be fixed by apache/skywalking-go#161

[wu-sheng]

From my understanding, the context could exit automatically once all spans are closed.