One-off Go blocking profile

[bboreham]

The goroutine dump /debug/pprof/goroutine can show you where things are blocked on a lock, but it can be much harder to figure out where the lock is held.

There is a blocking profile, but it must be enabled in code with runtime.SetBlockProfileRate(), and it records all events over a period. If I have a problem from blocking it will generally come up all the time, which is why a one-off dump is attractive.

(I'm assuming that, given an arbitrary lock, one can figure out something about where it is held. That may not be true)