Concurrent benchmarks of both sync.Map and a regular RWMutex locked map.

concurrent_bench.go

func benchmarkRegularStableKeys(b *testing.B, workerCount int) {
	runtime.GOMAXPROCS(workerCount)

	rm := NewRegularIntMap()
	populateMap(b.N, rm)

	var wg sync.WaitGroup
	wg.Add(workerCount)

	// Holds our final results, to prevent compiler optimizations.
	globalResultChan = make(chan int, workerCount)

	b.ResetTimer()

	for wc := 0; wc < workerCount; wc++ {
		go func(n int) {
			currentResult := 0
			for i := 0; i < n; i++ {
				currentResult, _ = rm.Load(5)
			}
			globalResultChan <- currentResult
			wg.Done()
		}(b.N)
	}

	wg.Wait()
}

func benchmarkSyncStableKeys(b *testing.B, workerCount int) {
	runtime.GOMAXPROCS(workerCount)

	var sm sync.Map
	populateSyncMap(b.N, &sm)

	var wg sync.WaitGroup
	wg.Add(workerCount)

	// Holds our final results, to prevent compiler optimizations.
	globalResultChan = make(chan int, workerCount)

	b.ResetTimer()

	for wc := 0; wc < workerCount; wc++ {
		go func(n int) {
			currentResult := 0
			for i := 0; i < n; i++ {
				r, ok := sm.Load(5)
				if ok {
					currentResult = r.(int)
				}
			}
			globalResultChan <- currentResult
			wg.Done()
		}(b.N)
	}

	wg.Wait()
}

func benchmarkRegularStableKeysFound(b *testing.B, workerCount int) {
	runtime.GOMAXPROCS(workerCount)

	rm := NewRegularIntMap()
	values := populateMap(b.N, rm)

	var wg sync.WaitGroup
	wg.Add(workerCount)

	// Holds our final results, to prevent compiler optimizations.
	globalResultChan = make(chan int, workerCount)

	b.ResetTimer()

	for wc := 0; wc < workerCount; wc++ {
		go func(n int) {
			currentResult := 0
			for i := 0; i < n; i++ {
				currentResult, _ = rm.Load(values[i])
			}
			globalResultChan <- currentResult
			wg.Done()
		}(b.N)
	}

	wg.Wait()
}

func benchmarkSyncStableKeysFound(b *testing.B, workerCount int) {
	runtime.GOMAXPROCS(workerCount)

	var sm sync.Map
	values := populateSyncMap(b.N, &sm)

	var wg sync.WaitGroup
	wg.Add(workerCount)

	// Holds our final results, to prevent compiler optimizations.
	globalResultChan = make(chan int, workerCount)

	b.ResetTimer()

	for wc := 0; wc < workerCount; wc++ {
		go func(n int) {
			currentResult := 0
			for i := 0; i < n; i++ {
				r, ok := sm.Load(values[i])
				if ok {
					currentResult = r.(int)
				}
			}
			globalResultChan <- currentResult
			wg.Done()
		}(b.N)
	}

	wg.Wait()
}

/*
// These tests do a lookup using a literal value.

// Regular Map backed by RWMutex
BenchmarkRegularStableKeys1-32          	50000000	        30.5 ns/op
BenchmarkRegularStableKeys2-32          	10000000	       157 ns/op
BenchmarkRegularStableKeys4-32          	 5000000	       377 ns/op
BenchmarkRegularStableKeys8-32          	 2000000	       701 ns/op
BenchmarkRegularStableKeys16-32         	 1000000	      1446 ns/op
BenchmarkRegularStableKeys32-32         	  500000	      2825 ns/op
BenchmarkRegularStableKeys64-32         	  200000	      5699 ns/op

// Sync Map
BenchmarkSyncStableKeys1-32             	20000000	        89.3 ns/op
BenchmarkSyncStableKeys2-32             	20000000	       101 ns/op
BenchmarkSyncStableKeys4-32             	 5000000	       247 ns/op
BenchmarkSyncStableKeys8-32             	 5000000	       330 ns/op
BenchmarkSyncStableKeys16-32            	 5000000	       295 ns/op
BenchmarkSyncStableKeys32-32            	 5000000	       269 ns/op
BenchmarkSyncStableKeys64-32            	 5000000	       249 ns/op

// These tests do a lookup of keys already defined in the map per iteration.

// Regular Map backed by RWMutex
BenchmarkRegularStableKeysFound1-32     	20000000	       114 ns/op
BenchmarkRegularStableKeysFound2-32     	10000000	       203 ns/op
BenchmarkRegularStableKeysFound4-32     	 3000000	       460 ns/op
BenchmarkRegularStableKeysFound8-32     	 2000000	       976 ns/op
BenchmarkRegularStableKeysFound16-32    	 1000000	      1895 ns/op
BenchmarkRegularStableKeysFound32-32    	  300000	      3620 ns/op
BenchmarkRegularStableKeysFound64-32    	  200000	      6762 ns/op

// Sync Map
BenchmarkSyncStableKeysFound1-32        	 5000000	       357 ns/op
BenchmarkSyncStableKeysFound2-32        	 3000000	       446 ns/op
BenchmarkSyncStableKeysFound4-32        	 3000000	       501 ns/op
BenchmarkSyncStableKeysFound8-32        	 3000000	       576 ns/op
BenchmarkSyncStableKeysFound16-32       	 2000000	       566 ns/op
BenchmarkSyncStableKeysFound32-32       	 3000000	       527 ns/op
BenchmarkSyncStableKeysFound64-32       	 2000000	       873 ns/op
*/

populateMap is not defined