versions

• go version go1.16.3 darwin/amd64
• go.elastic.co/apm v1.12.0
• go.elastic.co/apm/module/apmhttp v1.12.0

Bug

When the default http client is wrap with apmhttp.WrapClient(http.DefaultClient, apmhttp.WithClientTrace()) there is some case where an http request, will never answer. Even if the request has a context deadline.

To Reproduce

It is little hard to reproduce so I made code to reproduce it: https://github.com/AyWa/goapmdeadlock
I guess the scenario is like that:

• make many sub request that timeout concurrently. In my example I do 50 sub request concurrently https://github.com/AyWa/goapmdeadlock/blob/main/main.go#L68 * 100 times.

Expected behavior

The http.Client should not be in deadlock when wrap by apmhttp ( I think the deadlock happen for a given trace id so new request might work fine)