Revert "runtime: use semaphore structure for futex locks"
This reverts commit
dfb7073bb8e66630156fc14ae50042acef89a929 (CL 585636).
Reason for revert: This is part of a patch series that changed the
handling of contended lock2/unlock2 calls, reducing the maximum
throughput of contended runtime.mutex values, and causing a performance
regression on applications where that is (or became) the bottleneck.
Updates #66999
Updates #67585
Change-Id: I3483bf0b85ba0b77204032a68b7cbe93f142703e
Reviewed-on: https://go-review.googlesource.com/c/go/+/589098
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Rhys Hiltner <rhys.hiltner@gmail.com>