runtime/pprof: fix data race It's unclear why we do this broken double-checked locking. The mutex is not held for the whole duration of CPU profiling. Fixes issue 8365.
runtime/pprof: fix data race
It's unclear why we do this broken double-checked locking.
The mutex is not held for the whole duration of CPU profiling.
Fixes issue 8365.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/116290043

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