runtime: safe mutex initialization

_demo/sync/sync.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// Counter represents a thread-safe counter
+type Counter struct {
+	mu    sync.Mutex
+	value int64
+}
+
+// Increment increases the counter value by 1
+func (c *Counter) Increment() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	c.value++
+}
+
+// GetValue returns the current value of the counter
+func (c *Counter) GetValue() int64 {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.value
+}
+
+// Constant values for the test
+const (
+	numGoroutines = 64
+	numIterations = 10000
+	expectedTotal = numGoroutines * numIterations
+)
+
+func main() {
+	// Create a new counter instance
+	counter := &Counter{}
+
+	// Create a wait group to wait for all goroutines to finish
+	var wg sync.WaitGroup
+
+	// Track active goroutines for monitoring
+	var activeGoroutines int32
+
+	// Start time
+	startTime := time.Now()
+
+	// Launch goroutines
+	for i := 0; i < numGoroutines; i++ {
+		wg.Add(1)
+		atomic.AddInt32(&activeGoroutines, 1)
+
+		go func(id int) {
+			defer func() {
+				wg.Done()
+				atomic.AddInt32(&activeGoroutines, -1)
+			}()
+
+			// Each goroutine increments the counter numIterations times
+			for j := 0; j < numIterations; j++ {
+				counter.Increment()
+
+				// Simulate varying workload with random sleeps
+				if j%100 == 0 {
+					time.Sleep(time.Microsecond)
+				}
+			}
+			fmt.Printf("Goroutine %d finished\n", id)
+		}(i)
+	}
+
+	// Monitor progress in a separate goroutine
+	go func() {
+		for {
+			active := atomic.LoadInt32(&activeGoroutines)
+			if active == 0 {
+				break
+			}
+			fmt.Printf("Active goroutines: %d\n", active)
+			time.Sleep(time.Second)
+		}
+	}()
+
+	// Wait for all goroutines to complete
+	wg.Wait()
+
+	// Calculate execution time
+	duration := time.Since(startTime)
+
+	// Get and verify the final result
+	finalValue := counter.GetValue()
+	fmt.Printf("\nExecution completed in: %v\n", duration)
+	fmt.Printf("Final counter value: %d\n", finalValue)
+	fmt.Printf("Expected value: %d\n", expectedTotal)
+
+	// Assert the result
+	if finalValue != expectedTotal {
+		panic(fmt.Sprintf("ERROR: Counter value mismatch! Expected %d, got %d\n",
+			expectedTotal, finalValue))
+	} else {
+		fmt.Printf("SUCCESS: Counter value matches expected total\n")
+	}
+
+	// Print some statistics
+	opsPerSecond := float64(expectedTotal) / duration.Seconds()
+	fmt.Printf("\nStatistics:\n")
+	fmt.Printf("Operations per second: %.2f\n", opsPerSecond)
+	fmt.Printf("Average time per operation: %.2f ns\n",
+		float64(duration.Nanoseconds())/float64(expectedTotal))
+}