mirror of
https://github.com/golang/go
synced 2024-10-02 20:31:21 -06:00
40d81cf061
The panic leaves the lock in an unusable state. Trying to panic with a usable state makes the lock significantly less efficient and scalable (see early CL patch sets and discussion). Instead, use runtime.throw, which will crash the program directly. In general throw is reserved for when the runtime detects truly serious, unrecoverable problems. This problem is certainly serious, and, without a significant performance hit, is unrecoverable. Fixes #13879. Change-Id: I41920d9e2317270c6f909957d195bd8b68177f8d Reviewed-on: https://go-review.googlesource.com/31359 Reviewed-by: Austin Clements <austin@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
213 lines
4.2 KiB
Go
213 lines
4.2 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// GOMAXPROCS=10 go test
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package sync_test
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import (
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"fmt"
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"runtime"
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. "sync"
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"sync/atomic"
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"testing"
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)
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func parallelReader(m *RWMutex, clocked, cunlock, cdone chan bool) {
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m.RLock()
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clocked <- true
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<-cunlock
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m.RUnlock()
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cdone <- true
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}
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func doTestParallelReaders(numReaders, gomaxprocs int) {
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runtime.GOMAXPROCS(gomaxprocs)
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var m RWMutex
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clocked := make(chan bool)
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cunlock := make(chan bool)
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cdone := make(chan bool)
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for i := 0; i < numReaders; i++ {
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go parallelReader(&m, clocked, cunlock, cdone)
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}
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// Wait for all parallel RLock()s to succeed.
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for i := 0; i < numReaders; i++ {
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<-clocked
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}
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for i := 0; i < numReaders; i++ {
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cunlock <- true
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}
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// Wait for the goroutines to finish.
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for i := 0; i < numReaders; i++ {
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<-cdone
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}
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}
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func TestParallelReaders(t *testing.T) {
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1))
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doTestParallelReaders(1, 4)
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doTestParallelReaders(3, 4)
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doTestParallelReaders(4, 2)
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}
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func reader(rwm *RWMutex, num_iterations int, activity *int32, cdone chan bool) {
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for i := 0; i < num_iterations; i++ {
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rwm.RLock()
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n := atomic.AddInt32(activity, 1)
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if n < 1 || n >= 10000 {
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panic(fmt.Sprintf("wlock(%d)\n", n))
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}
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for i := 0; i < 100; i++ {
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}
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atomic.AddInt32(activity, -1)
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rwm.RUnlock()
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}
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cdone <- true
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}
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func writer(rwm *RWMutex, num_iterations int, activity *int32, cdone chan bool) {
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for i := 0; i < num_iterations; i++ {
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rwm.Lock()
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n := atomic.AddInt32(activity, 10000)
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if n != 10000 {
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panic(fmt.Sprintf("wlock(%d)\n", n))
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}
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for i := 0; i < 100; i++ {
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}
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atomic.AddInt32(activity, -10000)
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rwm.Unlock()
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}
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cdone <- true
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}
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func HammerRWMutex(gomaxprocs, numReaders, num_iterations int) {
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runtime.GOMAXPROCS(gomaxprocs)
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// Number of active readers + 10000 * number of active writers.
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var activity int32
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var rwm RWMutex
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cdone := make(chan bool)
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go writer(&rwm, num_iterations, &activity, cdone)
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var i int
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for i = 0; i < numReaders/2; i++ {
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go reader(&rwm, num_iterations, &activity, cdone)
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}
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go writer(&rwm, num_iterations, &activity, cdone)
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for ; i < numReaders; i++ {
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go reader(&rwm, num_iterations, &activity, cdone)
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}
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// Wait for the 2 writers and all readers to finish.
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for i := 0; i < 2+numReaders; i++ {
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<-cdone
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}
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}
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func TestRWMutex(t *testing.T) {
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defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(-1))
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n := 1000
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if testing.Short() {
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n = 5
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}
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HammerRWMutex(1, 1, n)
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HammerRWMutex(1, 3, n)
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HammerRWMutex(1, 10, n)
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HammerRWMutex(4, 1, n)
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HammerRWMutex(4, 3, n)
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HammerRWMutex(4, 10, n)
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HammerRWMutex(10, 1, n)
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HammerRWMutex(10, 3, n)
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HammerRWMutex(10, 10, n)
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HammerRWMutex(10, 5, n)
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}
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func TestRLocker(t *testing.T) {
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var wl RWMutex
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var rl Locker
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wlocked := make(chan bool, 1)
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rlocked := make(chan bool, 1)
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rl = wl.RLocker()
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n := 10
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go func() {
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for i := 0; i < n; i++ {
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rl.Lock()
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rl.Lock()
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rlocked <- true
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wl.Lock()
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wlocked <- true
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}
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}()
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for i := 0; i < n; i++ {
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<-rlocked
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rl.Unlock()
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select {
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case <-wlocked:
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t.Fatal("RLocker() didn't read-lock it")
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default:
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}
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rl.Unlock()
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<-wlocked
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select {
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case <-rlocked:
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t.Fatal("RLocker() didn't respect the write lock")
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default:
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}
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wl.Unlock()
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}
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}
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func BenchmarkRWMutexUncontended(b *testing.B) {
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type PaddedRWMutex struct {
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RWMutex
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pad [32]uint32
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}
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b.RunParallel(func(pb *testing.PB) {
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var rwm PaddedRWMutex
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for pb.Next() {
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rwm.RLock()
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rwm.RLock()
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rwm.RUnlock()
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rwm.RUnlock()
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rwm.Lock()
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rwm.Unlock()
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}
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})
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}
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func benchmarkRWMutex(b *testing.B, localWork, writeRatio int) {
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var rwm RWMutex
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b.RunParallel(func(pb *testing.PB) {
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foo := 0
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for pb.Next() {
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foo++
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if foo%writeRatio == 0 {
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rwm.Lock()
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rwm.Unlock()
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} else {
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rwm.RLock()
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for i := 0; i != localWork; i += 1 {
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foo *= 2
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foo /= 2
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}
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rwm.RUnlock()
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}
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}
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_ = foo
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})
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}
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func BenchmarkRWMutexWrite100(b *testing.B) {
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benchmarkRWMutex(b, 0, 100)
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}
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func BenchmarkRWMutexWrite10(b *testing.B) {
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benchmarkRWMutex(b, 0, 10)
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}
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func BenchmarkRWMutexWorkWrite100(b *testing.B) {
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benchmarkRWMutex(b, 100, 100)
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}
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func BenchmarkRWMutexWorkWrite10(b *testing.B) {
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benchmarkRWMutex(b, 100, 10)
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}
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