首次提交：初始化项目代码

gc_slice_prealloc.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"time"
+)
+
+// noPrealloc 未预分配容量，频繁扩容
+func noPrealloc() {
+	var data []int
+	for i := 0; i < 100000; i++ {
+		data = append(data, i)
+	}
+}
+
+// withPrealloc 预分配容量，无扩容
+func withPrealloc() {
+	data := make([]int, 0, 100000) // 预分配容量100000
+	for i := 0; i < 100000; i++ {
+		data = append(data, i)
+	}
+}
+
+func main() {
+	var stats runtime.MemStats
+
+	// 测试未预分配
+	runtime.GC()
+	start := time.Now()
+	noPrealloc()
+	dur1 := time.Since(start)
+	runtime.ReadMemStats(&stats)
+	fmt.Printf("未预分配：耗时%v，堆分配%d KB，GC次数%d\n", dur1, stats.HeapAlloc/1024, stats.NumGC)
+
+	// 测试预分配
+	runtime.GC()
+	start = time.Now()
+	withPrealloc()
+	dur2 := time.Since(start)
+	runtime.ReadMemStats(&stats)
+	fmt.Printf("预分配：耗时%v，堆分配%d KB，GC次数%d\n", dur2, stats.HeapAlloc/1024, stats.NumGC)
+}