The sync.Pool example returned buf.Bytes(). That slice points into the
pooled buffer. The deferred Reset and Put give the buffer to the next
Get, so another goroutine can overwrite the result while the caller
still uses it.
Return bytes.Clone(buf.Bytes()) instead, and add a short note. Same code
fix in the five translations. pi/core regenerated with
scripts/build-pi-core.js.
Tested: 64 goroutines calling the example under go test -race (Go 1.27).
Old code: DATA RACE and wrong results. New code: passes.
node scripts/build-pi-core.js --check passes.
Replaces the golang part of closed PRs #3351 and #3405, which were not
merged.
Dan
9c6499d770