51 lines
1.2 KiB
Go
51 lines
1.2 KiB
Go
package main
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import (
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"context"
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"fmt"
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"math/rand"
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"net/http"
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_ "net/http/pprof"
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"time"
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)
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// 来自文章 https://www.cnblogs.com/hwnd/p/20682814
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func simulateRequest() {
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timeout := 500 * time.Millisecond
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ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(timeout))
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defer cancel()
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resultCh := make(chan string) // 无缓冲！
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// 启动 worker goroutine 处理"请求"
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go func() {
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time.Sleep(time.Duration(rand.Intn(500)+300) * time.Millisecond)
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select {
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case <-time.After(timeout):
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fmt.Println("worker 超时，放弃处理")
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case <-ctx.Done():
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case resultCh <- fmt.Sprintf("处理完成，耗时 %dms", rand.Intn(500)+300):
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}
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}()
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// TODO: 模拟请求取消或超时的情况（比如 500ms 后调用方不再关心结果）
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// 如果 worker 还没完成，它就 leak 了
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select {
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case resultCh := <-resultCh:
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fmt.Println(resultCh)
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case <-ctx.Done():
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fmt.Println("请求方取消了请求")
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}
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}
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func main() {
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for i := 0; i < 5; i++ {
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simulateRequest()
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fmt.Printf("第 %d 个请求处理完毕\n\n", i+1)
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time.Sleep(200 * time.Millisecond)
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}
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fmt.Println("所有请求处理完毕")
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// 运行后观察：goroutine 数量只增不减
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http.ListenAndServe(":6060", nil)
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}
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