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