Currently the BenchmarkSetType* benchmarks are racy: they call
heapBitsSetType on an allocation that might be in a span in-use for
allocation on another P. Because heap bits are bits but are written
byte-wise non-atomically (because a P assumes it has total ownership of
a span's bits), two threads can race writing the same heap bitmap byte
creating incorrect metadata.
Fix this by forcing every value we're writing heap bits for into a large
object. Large object spans will never be written to concurrently unless
they're freed first.
Also, while we're here, refactor the benchmarks a bit. Use generics to
eliminate the reflect nastiness in gc_test.go, and pass b.ResetTimer
down into the test to get slightly more accurate results.
Fixes #60050.
Change-Id: Ib7d6249b321963367c8c8ca88385386c8ae9af1c
Reviewed-on: https://go-review.googlesource.com/c/go/+/497215 Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>