trace: make trace byte receiving synchronous

This avoids the asynchrony related to the pipe+buffer+goroutine. Using
this approach, we can guarantee that once the `Write` call completes,
the data is stored in flightrecorder buffers. This is related to

There is a behavioral change: previously, in case of error the recorder
goroutine would just stop, which would essentially block the tracing
infra by not accepting the `Write`. Now, we actively stop tracing on any

I did not do real performance tests, but it can't be very different:


    running go [test . -count 10]
    ok  60.423s


    running go [test . -count 10]
    ok  60.394s

Change-Id: Ie900fec2b45f1c227c82e68f4f7af1902de3582b
Reviewed-by: Michael Knyszek <>
Auto-Submit: Michael Knyszek <>
LUCI-TryBot-Result: Go LUCI <>
1 file changed
tree: 2a90bc7671824e9c903c5aed0676617b2a3aa196
  1. apidiff/
  2. cmd/
  3. constraints/
  4. ebnf/
  5. ebnflint/
  6. errors/
  7. event/
  8. inotify/
  9. io/
  10. jsonrpc2/
  11. maps/
  12. mmap/
  13. rand/
  14. shiny/
  15. shootout/
  16. slices/
  17. slog/
  18. sumdb/
  19. trace/
  20. typeparams/
  21. utf8string/
  22. .gitattributes
  23. .gitignore
  24. codereview.cfg
  26. go.mod
  27. go.sum



This subrepository holds experimental and deprecated (in the old directory) packages.

The idea for this subrepository originated as the pkg/exp directory of the main repository, but its presence there made it unavailable to users of the binary downloads of the Go installation. The subrepository has therefore been created to make it possible to go get these packages.

Warning: Packages here are experimental and unreliable. Some may one day be promoted to the main repository or other subrepository, or they may be modified arbitrarily or even disappear altogether.

In short, code in this subrepository is not subject to the Go 1 compatibility promise. (No subrepo is, but the promise is even more likely to be violated by go.exp than the others.)

Caveat emptor.