Add high contention benchmark.

mq/lib_test.go

@@ -2,6 +2,7 @@ package mq_test
 
 import (
 	"math/rand"
+	"runtime"
 	"sync"
 	"testing"
 
@@ -226,3 +227,64 @@ func BenchmarkConcSendRecvChan(b *testing.B) {
 	close(start)
 	wg.Wait()
 }
+
+func BenchmarkHighContention(b *testing.B) {
+	q := mq.Make[int](b.N)
+	var wg sync.WaitGroup
+	start := make(chan struct{})
+	done := make(chan struct{})
+	numProducers := runtime.NumCPU()
+	sendsPerProducer := b.N / numProducers
+	wg.Add(numProducers)
+	for i := 0; i < numProducers; i++ {
+		go func() {
+			<-start
+			for i := 0; i < sendsPerProducer; i++ {
+				q.Send(1)
+			}
+			wg.Done()
+		}()
+	}
+	go func() {
+		ok := true
+		for ok {
+			_, ok = q.Recv()
+		}
+		close(done)
+	}()
+	b.ResetTimer()
+	close(start)
+	wg.Wait()
+	q.Close()
+	<-done
+}
+
+func BenchmarkHighContentionChan(b *testing.B) {
+	c := make(chan int, b.N)
+	var wg sync.WaitGroup
+	start := make(chan struct{})
+	done := make(chan struct{})
+	numProducers := runtime.NumCPU()
+	sendsPerProducer := b.N / numProducers
+	wg.Add(numProducers)
+	for i := 0; i < numProducers; i++ {
+		go func() {
+			<-start
+			for i := 0; i < sendsPerProducer; i++ {
+				c <- 1
+			}
+			wg.Done()
+		}()
+	}
+	go func() {
+		for n := range c {
+			_ = n
+		}
+		close(done)
+	}()
+	b.ResetTimer()
+	close(start)
+	wg.Wait()
+	close(c)
+	<-done
+}